WE CLAIM:
1. A lithographic printing plate precursor comprising an image recording layer
containing an infrared absorber represented by Formula I, on a support:

in Formula I, each of X1 and X2 independently represents a sulfur atom, an oxygen atom, or a dialkylmethylene group having 12 or less carbon atoms, each of Y1 and Y2 independently represents a monovalent organic group or a hydrogen atom, each of Z1 and Z2 independently represents a benzene ring, a naphthalene ring, or a 6- to 20-membered heteroaromatic ring unsubstituted or substituted with an electron-donating group or an aryl group having from 6 to 20 carbon atoms, each of R1, R2, R3, and R4 independently represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms, each of R5 and R6 independently represents a hydrocarbon group which optionally forms a 5-membered ring or a 6-membered ring, each of R7, R8, R9, and R10 independently represents a hydrogen atom or a monovalent organic group, and A represents a counter ion present in a case in which charge neutralization is needed.
2. The lithographic printing plate precursor according to claim 1, wherein the
infrared absorber represented by Formula I is an infrared absorber represented by Formula II:


in Formula II, each of X1 and X2 independently represents a sulfur atom, an oxygen atom, or a dialkylmethylene group having 12 or less carbon atoms, each of Y1 and Y2 independently represents a monovalent organic group or a hydrogen atom, each of Z1 and Z2 independently represents a benzene ring, a naphthalene ring, or a 6- to 20-membered heteroaromatic ring unsubstituted or substituted with an electron-donating group or an aryl group having from 6 to 20 carbon atoms, each of R1, R2, R3, and R4 independently represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms, each of R7, R8, R9, and R10 independently represents a hydrogen atom or a monovalent organic group, and A represents a counter ion present in a case in which charge neutralization is needed.
3. The lithographic printing plate precursor according to claim 1 or 2, wherein the image recording layer further contains a polymerizable compound and a polymerization initiator.
4. The lithographic printing plate precursor according to claim 3, wherein the polymerization initiator is an iodonium-based polymerization initiator.
5. The lithographic printing plate precursor according to any one of claims 1 to 4, wherein the image recording layer further contains a thermoplastic polymer particle.
6. The lithographic printing plate precursor according to claim 5, wherein the polymer contained in the thermoplastic polymer particle contains any or both monomer units of a monomer unit derived from styrene and a monomer unit derived from an acrylic compound.
7. The lithographic printing plate precursor according to claim 5 or 6, wherein

the polymer contained in the thermoplastic polymer particle is a styrene-acrylonitrile resin.
8. The lithographic printing plate precursor according to any one of claims 5 to claim 7, wherein the weight average molecular weight of the polymer contained in the thermoplastic polymer particle is from 5,000 to 1,000,000.
9. The lithographic printing plate precursor according to any one of claims 5 to claim 8, wherein the volume average particle size of the thermoplastic polymer particle is from 0.01 μm to 50 μm.
10. The lithographic printing plate precursor according to any one of claims 5 to
9, wherein the content of the thermoplastic polymer particle with respect to the total mass of
the image recording layer is from 20% by mass to 95% by mass.
11. The lithographic printing plate precursor according to any one of claims 1 to
10, wherein the image recording layer further contains a leuco compound.
12. The lithographic printing plate precursor according to any one of claims 1 to
11, wherein the image recording layer is removable by any or both of dampening water and a
printing ink.
13. The lithographic printing plate precursor according to any one of claims 1 to
12, wherein the image recording layer is gum-developable.
14. A method of producing a lithographic printing plate, comprising:
an exposure step of image-wise exposing the lithographic printing plate precursor according to any one of claims 1 to 13, to form an exposed area and an unexposed area; and
an on-press development step of feeding at least one of a printing ink or dampening water to remove the unexposed area.
15. A lithographic printing method comprising:
an exposure step of image-wise exposing the lithographic printing plate precursor according to any one of claims 1 to 13, to form an exposed area and an unexposed area;
an on-press development step of feeding at least one of a printing ink or dampening water to remove the unexposed area; and

a printing step of feeding a printing ink to a lithographic printing plate subjected to on-press development in the on-press development step, to perform printing on a recording medium, in this order.