WE CLAIM:
1. A lithographic printing plate precursor comprising:
a support; and
an image-recording layer,
wherein the image-recording layer is capable of forming an image by infrared laser exposure, a non-exposed portion of the image-recording layer is removable by at least one of dampening water and printing ink on a printer, and the image-recording layer contains (1) a color developing system in which a hue change generated by infrared laser exposure is Aa/Ab>0.6 and (2) 70% by mass or more of a thermoplastic polymer particle with respect to a solid content of the image-recording layer.
2. The lithographic printing plate precursor according to claim 1,
wherein the image-recording layer contains 80% by mass or more of the thermoplastic polymer particle with respect to the solid content of the image-recording layer.
3. The lithographic printing plate precursor according to claim 1,
wherein the image-recording layer contains 90% by mass or more of the thermoplastic polymer particle with respect to the solid content of the image-recording layer.
4. The lithographic printing plate precursor according to any one of claims 1 to 3,
wherein the color developing system is formed of an infrared absorbing dye.
5. The lithographic printing plate precursor according to claim 4,
wherein the infrared absorbing dye is a compound represented by the following

wherein, in the Formula (1), R1 represents a group in which an R1-O bond is cleaved by heat or exposure to an infrared ray, R2 and R3 each independently represent a hydrogen

atom or an alkyl group, R2 and R3 may be linked to each other to form a ring, Ar1 and Ar2 each independently represent a group forming a benzene ring or a naphthalene ring, Y1 and Y2 each independently represent an oxygen atom, a sulfur atom, -NR0-, or a dialkyl methylene group, R4 and R5 each independently represent an alkyl group, R6 to R9 each independently represent a hydrogen atom or an alkyl group, R0 represents a hydrogen atom, an alkyl group, or an aryl group, and Za represents a counter ion that neutralizes a charge.
6. The lithographic printing plate precursor according to claim 4,
wherein the infrared absorbing dye is a compound having a cyanine colorant structure represented by the following General Formula (i) and having at least one solvent-soluble group in a molecule,

wherein, in the General Formula (i), X1 represents a hydrogen atom, a halogen atom, -NPh2, X2-L1, or a group described below, in which, X2 represents an oxygen atom, a nitrogen atom, or a sulfur atom, L1 represents a hydrocarbon group having 1 to 12 carbon atoms or a hydrocarbon group including a hetero atom and having 1 to 12 carbon atoms, in the group described below, Xa- is same as Za- described below, and Ra represents a hydrogen atom or a substituent selected from an alkyl group, an aryl group, a substituted or unsubstituted amino group, and a halogen atom,

R1 and R2 each independently represent a hydrocarbon group having 1 to 12 carbon atoms, R1 and R2 may be bonded to each other to form a five-membered ring or a six-membered ring, Ar1 and Ar2 may be identical to or different from each other and represent an aromatic hydrocarbon group, Y1 and Y2 may be identical to or different from each other and represent a sulfur atom or a dialkyl methylene group having 12 or less carbon atoms, R3 and R4 may be identical to or different from each other and represent a hydrocarbon group having 20 or less carbon atoms, R5, R6, R7, and R8 may be identical to or different from one another

and represent a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms, Za-represents a counter anion, provided that, the compound having a cyanine colorant structure represented by the General Formula (i) has an anionic substituent in the structure, and Za- is not required in a case in which neutralization of a charge is not necessary.
7. The lithographic printing plate precursor according to any one of claims 4 to 6,
wherein the image-recording layer further contains a color developing aid.
8. The lithographic printing plate precursor according to claim 7,
wherein the color developing aid is an iodonium salt or a sulfonium salt.
9. The lithographic printing plate precursor according to claim 7,
wherein the color developing aid is a borate compound.
10. The lithographic printing plate precursor according to any one of claims 1 to 3,
wherein the color developing system is formed of an infrared absorbing dye and a color developing precursor.
11. The lithographic printing plate precursor according to claim 10,
wherein the infrared absorbing dye is a cyanine colorant represented by the following General Formula (a),

wherein, in the General Formula (a), X1 represents a hydrogen atom, a halogen atom, -N(R9)(R10), X2-L1, or a group described below, in which, R9 and R10 may be identical to or different from each other and represent an aromatic hydrocarbon group having 6 to 10 carbon atoms, an alkyl group having 1 to 8 carbon atoms, or a hydrogen atom, or R9 and R10 may be bonded to each other to form a ring, X2 represents an oxygen atom, a nitrogen atom, or a sulfur atom, and L1 represents a hydrocarbon group having 1 to 12 carbon atoms or a hydrocarbon group including a hetero atom and having 1 to 12 carbon atoms, in the group described below,

Xa is same as Za- described below, and Ra represents a hydrogen atom or a substituent selected from an alkyl group, an aryl group, a substituted or unsubstituted amino group, and a halogen atom,

R1 and R2 each independently represent a hydrocarbon group having 1 to 12 carbon atoms, R1 and R2 may be bonded to each other to form a five-membered ring or a six-membered ring, Ar1 and Ar2 may be identical to or different from each other and represent an aromatic hydrocarbon group, Y1 and Y2 may be identical to or different from each other and represent a sulfur atom or a dialkyl methylene group having 12 or less carbon atoms, R3 and R4 may be identical to or different from each other and represent a hydrocarbon group having 20 or less carbon atoms, R5, R6, R7, and R8 may be identical to or different from one another and represent a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms, Za-represents a counter anion, provided that, the cyanine colorant represented by the General Formula (a) has an anionic substituent in the structure, and Za- is not required in a case in which neutralization of a charge is not necessary.
12. The lithographic printing plate precursor according to claim 10 or 11,
wherein the color developing precursor is an acid color developer.
13. The lithographic printing plate precursor according to claim 10 or 11,
wherein the color developing precursor is a thermal color developer.
14. The lithographic printing plate precursor according to claim 12,
wherein the image-recording layer further contains an acid-generating agent.
15. The lithographic printing plate precursor according to claim 14,
wherein the acid-generating agent is an iodonium salt, a sulfonium salt, or an azinium salt.
16. A plate-making method, comprising:
carrying out image exposure on the lithographic printing plate precursor according to any one of claims 1 to 15 using an infrared laser; and

removing a non-exposed portion of the image-recording layer by at least one of dampening water and printing ink on a printer.
17. The plate-making method according to claim 16,
wherein the image exposure by the infrared laser is carried out at a surface exposure intensity of 50 to 150 mJ/cm2.