DESCRIPTION ELEVATOR SAFETY APPARATUS TECHNICAL FIELD .. [0001] The present invention relates to an elevator safety apparatus that can brake running of a car in either vertical direction. BACKGROUNDART [0002] Conventionally, elevator apparatuses have been proposed that include a wedge-type emergency stop device in which braking is activated electrically if an elevator abnormality has occurred. In these conventional elevator apparatuses, a braking force is applied to a car by displacing a wedge using an electromagnetic actuator to engage the wedge between a guide rail that guides the car and a bracket that is disposed on the car (see Patent Literature 1, for example). [0003] Conventionally, elevator safety apparatuses have also been proposed that perform the car braking action by combining actions of a pair of electromagnets to pivot a pivoting member vertically. A top braking shoe and a bottom braking shoe are disposed on the pivoting member. A guide rail that guides the car is gripped between the bottom braking shoe and a fixed shoe by upward pivoting of the pivoting member, and is gripped between the top braking shoe and the fixed shoe by downward pivoting of the pivoting member. The car is braked by the guide rail being gripped between either the top braking shoe or the bottom braking shoe and the fixed shoe (see Patent Literature 2, for example). [0004] [Patent Literature 1] WO2004/083091 [Patent Literature 2] European Patent Application Publication No. 1460020 (Specification) DISCLOSURE OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION [0005] However, in the elevator apparatus that is disclosed in Patent Literature 1, a plurality of emergency stop devices that pei'orm a braking action individually either in an upward direction or in a downward direction must be mounted to the car. Consequently, in order to perform a braking action on the car in either vertical direction, the emergency stop device as a whole is enlarged. [0006] In the elevator safety apparatus that is disclosed in Patent Literature 2, because a pair of electromagnets must be used in order to pivot the pivoting member, the drive portion is also enlarged. [0007] The present invention aims to solve the above problems and an object of the present invention is to provide an elevator safety apparatus that can achieve reductions in size, and that can perform a car braking action in either vertical direction more reliably and in a shorter amount of time. MEANS FOR SOLVING THE PROBLEM [0008] In order to achieve the above object, according to one aspect of the present invention, there is provided an elevator safety apparatus characterized in including: a housing that is supported by a car that is guided by a guide rail, and that is displaceable horizontally relative to the car; a bearing rail stopper that is disposed on the housing; a pivoting rail stopper that is disposed on the housing such that the guide rail is disposed between the pivoting rail stopper and the bearing rail stopper, and that can be pivoted vertically such that a distance to the bearing rail stopper is reduced by the vertical pivoting; and a displacement driving mechanism that displaces the housing relative to the car in a direction in which the pivoting rail stopper separates from and contacts with the guide rail, the guide rail being gripped between the pivoting rail stopper and the bearing rail stopper by the pivoting rail stopper being pivoted in a direction that corresponds to a direction of movement of the car while contacting the guide rail. BRIEF DESCRIPTION OF THE DRAWINGS [0009] Figure 1 is a structural diagram that shows an elevator apparatus according to Embodiment 1 of the^resent invention; Figure 2 is a structural cliagram that shows an emergency stopping apparatus from Figure 1; Figure 3 is a cross section that has been taken along line III - III in Figure 2; Figure 4 is a side elevation of the emergency stopping apparatus in Figure 2; Figure 5 is a structural diagram that shows a state in which a central contacting surface of a pivoting rail stopper from Figure 2 contacts a car guide rail; Figure 6 Is a cross section that has been taken along line VI - VI in Figure 5; Figure 7 is a structural diagram that shows a state in which a lower frictional surface of the pivoting rail stopper from Figure 2 contacts the car guide rail; Figure 8 is a cross section that has been taken along line VIII - VIII in Figure 7; Figure 9 is a structural diagram that shows an emergency stopping apparatus according to Embodiment 2 of the present invention; Figure 10 is a cross section that has been taken along line X - X in Figure 9; Figure 11 is a cross section that has been taken along line XI - XI in Figure 9; Figure 12 is a structural diagram that shows a state in which a central contacting surface of a pivoting rail stopper from Figure 9 contacts a car guide rail; Figure 13 is a cross section that has been taken along line XIII - XIII in Figure 12; Figure 14 is a structural diagram that shows a state in which a lower frictional surface of the pivoting rail stopper from Figure 9 contacts the car guide rail; and Figure 15 is a cross section that has been taken along line XV - XV in Figure 14. BEST MODE FOR CARRYING OUT THE INVENTION [0010] "^ Preferred embodiments of the present invention will now be expsained withf eference to the drawings. •? Embodiment 1 Figure 1 is a structural diagram that shows an elevator apparatus according to Embodiment 1 of the present invention. In the figure, a car 1 and a counterweight (not shown) are suspended by a main rope 2. The main rope 2 is wound around a drive sheave of a hoisting machine. The drive sheave is rotated by a driving force from the hoisting machine. The car 1 and the countenA^eight are raised and lowered inside a hoistway by the rotation of the drive sheave. A pair of car guide rails 3 that guide raising and lowering of the car 1, and a pair of countenweight guide rails (not shown) that guide raising and lowering of the counterweight are installed in the hoistway. [0011] The raising and lowering of the car 1 and the counterweight are controlled by an elevator control board 4. Respective information from a car speed detecting sensor 5 that detects speed of the car 1, a door opening and closing detecting sensor 6 that detects whether a doorway (not shown) of the car 1 is open or closed, and a main rope breal; enabling the number of braking actions to be increased. [0063] Because positions of an upper braking shoe 27 and a lower braking shoe 28 relative to a pivoting rail stopper main body 26 are adjustable by adjustment of thicknesses of spacers 45 and 46, if gripping force on the car guide rail 3 has been reduced by abrasion, etc., of the upper braking shoe 27 and the lower braking shoe 28, for example, the gripping force can be restored by adjusting the positions of the upper braking shoe 27 and the lower braking shoe 28. =f- [0064] e Because pressing elements 22 that press the bearing rail stopper 17 against the car guide rail 3 are disposed between the bearing rail stopper 17 and the housing 13, gripping force on the car guide rail 3 can be generated more reliably. Thus, braking force can be applied to the car 1 more reliably. [0065] Because presence or absence of an elevator abnormality is detected by a braking command portion 8 based on respective information from a car speed detecting sensor 5, a door opening and closing detecting sensor 6, and a main rope breakage detecting sensor 7, and braking action of the emergency stopping apparatuses 9 is performed on detection of an abnormality by the braking command portion 8, a braking force can be applied to the car 1 more reliably and in a shorter amount of time if an abnormality occurs in the speed of the car 1, if the car 1 moves with the doonway of the car 1 open, or if the main rope 2 breaks. [0066] Moreover, in the above example, respective amounts of protrusion of the upper braking shoe 27 and the lower braking shoe 28 from the pivoting rail stopper main body 26 are approximately identical, but the amount of protrusion of the upper braking shoe 27 may also be made less than the amount of protrusion of the lower braking shoe 28. The braking force required to stop the ascending car 1 when balance between the car 1 and the countenweight is uneven may be smaller than the braking force required to stop the descending car 1 if the main rope 2 breaks. Consequently, the braking force required during the ascent of the car 2 can be made smaller than the braking force required during the descent of the car 1 by making the amount of protrusion of the upper braking shoe 27 less than the amount of protrusion of the lower braking shoe 28, enabling a braking force that corresponds to the direction of movement of the car 1 to be applied to the car 1. [0067] In the above example, the rail contacting surface of the pivoting rail stopper 18 is constituted by a flat surface 26a, and cylindrical surfaces 26b and 26c that are centered around positions Pup and Pdn that are respectively offset upward and downward from a pivoting center Cn, but the rail contacting surface is not limited to this shape, and may also be shaped su-^h that the main shaft 24 separates from the car guide rail 3 continuously as L,e pivoting rail stopper 18 is pivoted while contacting the car guide rail 3. [0068] Embodiment 2 Figure 9 is a structural diagram that shows an emergency stopping apparatus 9 according to Embodiment 2 of the present invention. Figure 10 is a cross section that has been taken along line X - X in Figure 9, and Figure 11 is a cross section that has been taken along line XI - XI in Figure 9. In the figures, a housing 13 has: a housing main body 51; and an upper mounting guide portion 52 and a lower mounting guide portion 53 that are disposed on the housing main body 51, and that are arranged so as to be spaced apart from each other in a vertical direction. [0069] The upper mounting guide portion 52 and the lower mounting guide portion 53 project toward a car guide rail 3 from the housing main body 51. The upper mounting guide portion 52 has: a horizontal portion; and a bearing portion that extends downward from an end portion of the horizontal portion at an opposite end from the car guide rail 3. The lower mounting guide portion 53 has: a horizontal portion; and a bearing portion that extends upward from an end portion of the horizontal portion at an opposite end from the car guide rail 3. [0070] A bearing rail stopper 17 is disposed between the upper mounting guide portion 52 and the lower mounting guide portion 53. The bearing rail stopper 17 is guided relative to the housing 13 along the respective horizontal portions of the upper mounting guide portion 52 and the lower mounting guide portion 53. [0071] A plurality of (in this example, two) shoulder bolts 19 that are disposed horizontally are fixed to the bearing rail stopper 17. Each of the shoulder bolts 19 extends toward a back surface of the bearing rail stopper 17. Each of the shoulder bolts 19 passes through a common backing plate (a restricting portion) 54 that is disposed between the upper mounting guide portion 52 and the lower mounting guide portion 53. [0072] 5J A plurality of (in this ex:^mple, two) pressing force adjusting bolts (adjusting elements) 55 through which the respective shoulder bolts 19 pass are screwed into the backing plate 54. The pressing force adjusting bolts 55 are slidable horizontally relative to the shoulder bolts 19. [0073] Pressing elements 22 through which the shoulder bolts 19 are passed are respectively disposed between the bearing rail stopper 17 and the respective pressing force adjusting bolts 55 (i.e., on an opposite side of the bearing rail stopper 17 from the car guide rail 3). The pressing elements 22 have a plurality of disk springs, for example. The pressing elements 22 force the bearing rail stopper 17 away from the backing plate 54 using elastic resilience due to the disk springs being compressed. [0074] The pressing force adjusting bolts 55 adjust the magnitude of the elastic resilience of the pressing elements 22. Adjustment of the elastic resilience of the pressing elements 22 is performed by the adjusting an amount of thread engagement of the pressing force adjusting bolts 55 in the backing plate 54. [0075] Each of the shoulder bolts 19 is passed through a washer 20, and is screwed into a positioning nut 21. Displacement of the bearing rail stopper 17 away from the backing plate 54 is restricted by the engagement of the washers 20 and the positioning nuts 21 with the backing plate 54. Adjustment of the position of the bearing rail stopper 17 relative to the backing plate 54 is performed by adjusting an amount of thread engagement of the positioning nuts 21 on the shoulder bolts 19. [0076] The bearing rail stopper 17 is displaceable relative to the housing 13 together with each of the shoulder bolts 19, the washers 20, the positioning nuts 21, the pressing elements 22, the backing plate 54, and the pressing force adjusting bolts 55. When the bearing rail stopper 17 is displaced toward the backing plate 54, the pressing elements 22 generates even larger elastic resilience in opposition to the displacement of the bearing rail stopper 17. [0077] A plurality of (in this example, two) forcing springs 68 are disposed so as to be compressed between the bearing portion of the upper mouni^ng guide psrtion 52 and the bearing rail stopper 17 and between the bearing -portion of the lower mounting guide portion 53 and the bearing rail stopper 17, respectively. In other words, the bearing rail stopper 17 is forced horizontally away from each of the bearing portions of the upper mounting guide portion 52 and the lower mounting guide portion 53 by the respective forcing springs 68. [0078] A gap adjusting bolt 56 that passes horizontally through the backing plate 54 is screwed into a portion of the backing plate 54 between each of the shoulder bolts 19. A locknut 57 for preventing displacement of the gap adjusting bolt 56 relative to the backing plate 54 is screwed onto the gap adjusting bolt 56. [0079] A lever passage aperture 58 is disposed on the housing main body 51. A holding lever 59 that is engaged with the gap adjusting bolt 56 is passed through the lever passage aperture 58. The bearing rail stopper 17 is displaced relative to the housing 13 while the gap adjusting bolt 56 is engaged with the holding lever 59. A distance between the holding lever 59 and the backing plate 54 is adjusted by adjusting the amount of thread engagement of the gap adjusting bolt 56 in the backing plate 54. The distance between the bearing rail stopper 17 and the pivoting center Cn can thereby be adjusted. [0080] An electromagnet 60 is disposed on a portion of the housing 13 on an opposite side from the car guide rail 3. The electromagnet 60 has: a fixed core (a first core) 61 that is fixed to the housing 13; an electromagnetic coil 62 that is installed in the fixed core 61; and a movable core (a second core) 63 that is displaceable relative to the fixed core 61. The fixed core 61 and the movable core 63 can be attracted to each other by passing an electric current to the electromagnetic coil 62 (i.e., excitation of the electromagnet 60), and can be separated from each other in the direction of displacement of the housing 13 by stopping the passage of electric current to the electromagnetic coil 62. [0081] A lever mounting member is fixed to the fixed core 61. One end portion of the holding lever 59 is pivotably mounted to the lever mounting member by means of a pivoting support pin 64. An end portion of the gap adjusting bolt 56 near the bearing rail stopper 17 is pressed against a second end portion of the holding lever 59. ¥ [0082] ^c A pushing pin 65 that is disposedzhorizontally is fixed centrally on the movable core 63. The pushing pin 65 passes centrally through the fixed core 61. An adjusting nut 66 that restricts displacement of the fixed core 61 away from the movable core 63 is screwed onto the pushing pin 65. Magnitude of a gap between the movable core 63 and the fixed core 61 can be set to a predetermined value by adjusting a position of the adjusting nut 66 relative to the pushing pin 65. [0083] An intermediate portion of the holding lever 59 can be placed in contact with a tip end portion of the pushing pin 65. A gap distribution adjusting bolt (a housing position adjusting means) 67 that can be placed in contact with an intermediate portion of the holding lever 59 is mounted to the mounting frame 10. " [0084] The respective intermediate portions of the holding lever 59 are placed in contact with the pushing pin 65 and the gap distribution adjusting bolt 67 when the fixed core 61 and the movable core 63 are attracted to each other. Both the bearing rail stopper 17 and the pivoting rail stopper 18 are thereby held away from the car guide rail 3. Specifically, when the fixed core 61 and the movable core 63 are attracted to each other, displacement of the bearing rail stopper 17 toward the car guide rail 3 is restricted by the pushing pin 65 stopping the pivoting of the holding lever 59, and displacement of the pivoting rail stopper 18 toward the car guide rail 3 is restricted by the gap distribution adjusting bolt 67 stopping displacement of the housing 13. [0085] A position at which displacement of the housing 13 is restricted by the gap distribution adjusting bolt 67 can be adjusted by adjusting an amount of thread engagement of the gap distribution adjusting bolt 67 in the mounting frame 10. In other words, gap dimensions between the car guide rail 3 and the pivoting rail stopper 18 and between the car guide rail 3 and the bearing rail stopper 17 (Figures 9 and-10) can be adjusted by adjusting the amount of thread engagement of the gap distribution adjusting bolt 67 in the mounting frame 10. [0086] Th0 housing 13 is displaced to the right in Figure 10 by spring forces? from eacteof the forcing springs 30 and 68 when the fixed core 61 and thfe^. movable core 63 are separated from each other, pivoting the holding lever 5Q: counterclockwise in Figure 10. In other words, the housing 13 and the holding lever 59 are displaced when the fixed core 61 and the movable core 63 are separated from each other such that the bearing rail stopper 17 and the pivoting rail stopper 18 are displaced toward each other. Thus, the bearing rail stopper 17 and the pivoting rail stopper 18 each contact the car guide rail 3. [0087] A plurality of (in this example, two) center of gravity adjusting apertures 69 are disposed on the pivoting rail stopper main body 26. The center of gravity of the pivoting rail stopper 18 is thereby aligned with the pivoting center Cn. In this example, the center Pup of the upper contacting curved surface 26b is positioned near the Y-axis in a first quadrant of X - Y coordinates that are centered around the pivoting center Cn, and the center Pdn of the lower contacting cun/ed surface 26c is positioned near the Y-axis in a fourth quadrant. In addition, a bearing 25 between the pivoting rail stopper 18 and the main shaft 24 is a rolling bearing. [0088], Moreover, a displacement driving mechanism 29 includes the respective forcing springs 30 and a holding and releasing mechanism (a holding means). The holding and releasing mechanism (the holding means) includes the holding lever 59, the electromagnet 60, the pushing pin 65, and the gap distribution adjusting bolt 67. In addition, a rail stopper interval adjusting means that adjusts a distance between the pivoting center Cn of the pivoting rail stopper 18 and the bearing rail stopper 17 includes the backing plate 54, the gap adjusting bolt 56; the locknut 57, and the respective forcing springs 68. The rest of the configuration is similar to that of Embodiment 1. [0089] Next, operation will be explained. Figure 12 is a structural diagram that shows a state in which the central contacting surface 26a of the pivoting rail stopper 18 from Figure 9 contacts the car guide rail 3, and Figure 13 is a cross section that has been taken along line XIII - XIII in Figure 12. Figure 14 is a structural diagram that shows a state in which the lower frictional surface 28a of the pivoting rail stopper 18 from Figure 9 contacts the car guide rail 3, and Figure 15 is a cross section that has been %aken along line XV - XV in Figure 14. -^ [0090] -: During normal operation, as shown in Figures 9 and 10, the electromagnet 60 is excited by control from the control board 4 such that the fixed core 61 and the movable core 63 are attracted to each other. Here, displacement of the bearing rail stopper 17 toward the car guide rail 3 (displacement to the left in Figure 10) is restricted by the holding lever 59, and displacement of the pivoting rail stopper 18 toward the car guide rail 3 (displacement to the right in Figure 10) is restricted by the gap distribution adjusting bolt 67. Both the pivoting rail stopper 18 and the bearing rail stopper 17 are thereby separated from the car guide rail 3 by a predetermined gap. [0091] If the"^displacement driving mechanism 29 of each of the emergency stopping apparatuses 9 receives a braking command, the passage of electric current to the electromagnetic coil 62 is stopped, and the holding force from the electromagnet 60 is lost. When the holding force from the electromagnet 60 is lost, the fixed core 61 and the movable core 63 are displaced away from each other by the forces from the forcing springs 30 and 68. The housing 13 is thereby displaced together with the fixed core 61, displacing the pivoting rail stopper 18 toward the car guide rail 3 (to the right in Figure 10). Here, the holding lever 59 is also pivoted counterclockwise in Figure 10, displacing the bearing rail stopper 17 toward the car guide rail 3. [0092] As shown in Figures 12 and 13, the bearing rail stopper 17 and the pivoting rail stopper 18 subsequently contact the car guide rail 3. The bearing rail stopper 17 is subsequently pressed onto the car guide rail 3 by the forces from the respective forcing springs 68, and the pivoting rail stopper 18 is pressed onto the car guide rail 3 by the forces from the respective forcing springs 30. Moreover, the forces from the forcing springs 30 and 68 are set such that these pressing forces balance each other. [0093] Next, if the car 1 is descending, the pivoting rail stopper 18 is pulled by the car guide rail 3 so as to be pivoted upward. Here, the lower contacting curved surface 26c of the pivoting rail stopper 18 is pivoted while contacting the car guide rail 3 -^ue to the respective forces from the forcing springs 30. The housing 13 is tfsareby displaced in a direction in which the main shaft 24 separates from the car guide rail 3 (to the left in Figure 12). [0094] As the pivoting rail stopper 18 is subsequently pivoted further, and the housing 13 is displaced in a direction in which the main shaft 24 separates from the car guide rail 3, each of the bearing portions of the upper mounting guide portion 52 and the lower mounting guide portion 53 engages with the backing plate 54, further compressing the pressing elements 22. [0095] As the lower braking shoe 28 reaches the car guide rail 3, the car guide rail 3 is gripped between the lower braking shoe 28 and the bearing rail stopper 17 (Figures 14 and 15). Here, the pressing elements 22 are compressed by the displacement of the bearing rail stopper 17 that is pushed by the car guide rail 3, generating elastic resilience that presses the bearing rail stopper 17 against the car guide rail 3. The lower frictional surface 28a of the lower braking shoe 28 also contacts the car guide rail 3. The gripping force on the car guide rail 3 is thereby ensured, imparting a braking force to the car 1. [0096] On the other hand, if the pivoting rail stopper 18 contacts the car guide rail 3 when the car 1 is ascending, the pivoting rail stopper 18 is pulled by the car guide rail 3 so as to be pivoted downward. Here, the upper contacting curved surface 26b of the pivoting rail stopper 18 is pivoted while contacting the car guide rail 3 due to the respective forces from the forcing springs 30. The housing 13 is thereby displaced in a direction in which the main shaft 24 separates from the car guide rail 3. [0097] As the pivoting rail stopper 18 is subsequently pivoted further, and the housing 13 is displaced in a direction in which the main shaft 24 separates from the car guide rail 3, each of the bearing portions of the upper mounting guide portion 52 and the lower mounting guide portion 53 engages with the backing plate 54, further compressing the pressing elements 22. [0098] As the upper braking shoe 27 subsequently reaches the car guide rail 3, the car guide rail 3 is gripped between the upper braking shoe 27 and the bearing rail stopper 17. Here, the pressing elements 22 are compressed by the displacement of the bearing rail stopper 17 that is pusi^rsd by the car guide rail 3, generating elastic resilience that presses the bearing rail stopper 17 against the car guide rail 3. The upper frictional surface 27a of the upper braking shoe 27 also contacts the car guide rail 3. The gripping force on the car guide rail 3 is thereby ensured, imparting a braking force to the car 1. [0099] In an elevator safety apparatus of this kind, because a bearing rail stopper 17 is displaced in a reverse direction to a direction in which a housing 13 is displaced, distances between a car guide rail 3 and a bearing rail stopper 17 and between the car guide rail 3 and a pivoting rail stopper 18 can be widened during normal operation, further enabling prevention of malfunction as a result of the car 1 inclining. [0100] Because adjustment of elastic resilience of pressing elements 22 is performed by adjusting an amount of thread engagement of pressing force adjusting bolts 55 in a backing plate 54, pressing force from the bearing rail stopper 17 onto the car guide rail 3 can be adjusted easily. [0101] Because a center of gravity of the pivoting rail stopper 18 is aligned with a pivoting center Cn of the pivoting rail stopper 18, pivoting of the pivoting rail stopper 18 can be prevented even if rocking, etc., of the car 1 arises, for example. [0102] Moreover, in the above example, the center of gravity of the pivoting rail stopper 18 is aligned with the pivoting center Cn of the pivoting rail stopper 18, but the center of gravity of the pivoting rail stopper 18 may also be positioned below the pivoting center Cn on the Y-axis. Pivoting of the pivoting rail stopper 18 that occurs due to rocking, etc., of the car 1 can also be prevented in this manner. [0103] In the above example, the pressing force adjusting bolts 55 are screwed into the backing plate 54, but may also be screwed into a back surface of the bearing rail stopper 17. In addition, sensors are not limited to the car speed detecting sensor 5, the door opening and closing WHAT IS CLAIMED IS: 1. An elevator safety apparatus characterized in comprising: a housing that is supported by a car that is guided by a guide rail, and that is displaceable horizontally relative to the car; a bearing rail stopper that is disposed on the housing; a pivoting rail stopper that is disposed on the housing that the guide rail is disposed between the pivoting rail stopper and this; bearing rail stopper, and that can be pivoted vertically such that a distance to the bearing rail stopper is reduced by the vertical pivoting; and a displacement driving mechanism that displaces the housing relative to the car in a direction in which the pivoting rail stopper separates from and contacts with the guide rail, the guide rail being gripped between the pivoting rail stopper and the bearing rail stopper by the pivoting rail stopper being pivoted in a direction that corresponds to a direction of movement of the car while contacting the guide rail. 2. An elevator safety apparatus according to Claim 1, characterized in that the displacement driving mechanism comprises: a forcing body that forces the housing in a direction in which the pivoting rail stopper contacts the guide rail; and a holding means that can restrict displacement of the housing in opposition to force from the forcing body. 3. An elevator safety apparatus according to Claim 2, characterized in that the holding means comprises an electromagnet that restricts displacement of the housing by excitation, and that performs release of the restriction by stopping the excitation. 4. An elevator safety apparatus according to Claim 1, characterized in that the bearing rail stopper and the pivoting rail stopper are displaced together with the housing. 5. An elevator safety apparatus according to Claim 1, characterized in that the bearing rail stopper is displaceable relative to the housing, the pivoting rail stopper can be displaced together with the housing, and the displacement driving mechanism displaces the bearing rail stopper in a reverse direction to a direction in which the housing is displaced. 6. An elevator safety apparatus according to Claim 1, characterized in that the displacement driving mechanism comprises: a housing position adjusting means that can adjust a pu'^ition of the housing relative to the guide rail; and a rail stopper interval adjii ^ting means that can adjust a distance between a pivoting center of the pivoting rail stopper and the bearing rail stopper. 7. An elevator safety apparatus according to Claim 1, characterized in that: a rail contacting surface that includes a curved surface portion, and flat surface portions that are adjacent to an upper end and a lower end of the rail contacting surface are disposed on the pivoting rail stopper; and the curved surface portion contacts the guide rail when the pivoting rail stopper is pivoted while contacting the guide rail, and the flat surface portion contacts the guide rail when the guide rail is gripped between the pivoting rail stopper and the bearing rail stopper. 8. An elevator safety apparatus according to Claim 1, characterized in that: the pivoting rail stopper comprises a pivoting rail stopper main body; and a pair of braking shoes that are disposed on the pivoting rail stopper main body and that contact the guide rail when the guide rail is gripped between the pivoting rail stopper and the bearing rail stopper; and a position of each of the braking shoes relative to the pivoting rail stopper main body is adjustable. 9. An elevator safety apparatus according to Claim 1, characterized in that a center of gravity of the pivoting rail stopper is aligned with a pivoting center of the pivoting rail stopper. 10. An elevator safety apparatus according to Claim 1, characterized in further comprising a pressing element that presses the bearing rail stopper against the guide rail when the guide rail is gripped between the bearing rail stopper and the pivoting rail stopper. 11. An elevator safety apparatus according to Claim 10, characterized in that the pressing element and an adjusting element are disposed so as to overlap with each other between the bearing rail stopper and a restricting portiorrtiy which displacement away from the bearing rail stopper is restrii:*3d; and ~ 5- "the adjusting element is a pressing force adjusting bolt that adjusts a pressing force from the pressing element by adjusting an amount of thread engagement relative to at least one of the bearing rail stopper and the restricting portion. 12. An elevator safety apparatus according to Claim 1, characterized in further comprising a determining portion that detects presence or absence of an elevator abnormality and outputs a braking command based on at least one of a car speed detecting portion that detects speed of the car, a door opening and closing detecting portion that detects whether a doorway of the car is open or closed, and a main rope breakage detecting portion that detects presence or absence of a breakage of a main rope that suspends the car, and the displacement driving mechanism displaces the housing in a direction in which the pivoting rail stopper contacts the guide rail due to receiving the braking command. detecting sensor 6, and the main rope breakage detecting sensor 7.