Patent ID: 8603729

Claim:
A lithographic printing plate precursor comprising, in the following order: a support; an image-recording layer which is capable of forming an image by removing an unexposed area with at least one of printing ink and dampening water on a printing machine after exposure and contains (A) an infrared absorbing dye, (B) a polymerization initiator, (C) a polymerizable compound and (D) a binder polymer having an alkylene oxide group; and a protective layer containing (E) a hydrophilic polymer containing at least a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2): wherein, in the formulae (1) and (2), R 1 and R 4 each independently represents a hydrogen atom or a methyl group, R 2 and R 3 are hydrogen atoms, and R 5 is an unsubstituted straight-chain, branched or cyclic alkyl group having from 2 to 8 carbon atoms.