Method of preparing planographic printing plate

Abstract

A planographic printing plate manufacturing method is disclosed which comprises the step of developing a presensitized planographic printing plate with a developer with a pH of from 11.5 to less than 12.5 which does not substantially contain an organic solvent, wherein the presensitized planographic printing plate comprises a support having a roughened hydrophilic surface with a center line average surface roughness Ra of from 0.5 to 0.8 μm, and provided thereon, a photopolymerizable light sensitive layer and an oxygen shielding layer in that order, the photopolymerizable light sensitive layer containing A) an addition polymerizable monomer having an ethylenic double bond, B) a photopolymerization initiator, C) a sensitizing dye, and D) a polymer binder, and the oxygen shielding layer containing E) polyvinyl alcohol and F) polyvinyl pyrrolidone.

Dependencies are inferred from the claim text.