Patent ID: 6875557

Claim:
A plate-making method of a printing plate comprising exposing a printing plate precursor comprising an aluminum support provided thereon with a photosensitive layer comprising a photopolymerizable composition containing (i) a crosslinking agent having two ethylenic polymerizable groups and (ii) a crosslinking agent having three or more ethylenic polymerizable groups to a laser having a wavelength of from 350 to 1,200 nm, and development processing the exposed printing plate precursor with an alkali developer having a pH of not more than 12.5 wherein the alkali developer contains an inorganic alkali agent and a nonionic compound represented by the following formula (20): A-W (20) wherein A represents a hydrophobic organic group having a log P of A-H of not less than 1.5; and W represents a nonionic hydrophilic group having a log P of W-H of less than 1.0.