Method of preparing lithographic printing plate

摘要

A method for preparing a lithographic printing plate, includes: exposing imagewise a lithographic printing plate precursor including a hydrophilic support and an image-recording layer containing a sensitizing dye, a polymerization initiator, an addition polymerizable compound having an ethylenically unsaturated double bond and a binder polymer; and processing the imagewise exposed lithogaphic printing plate precursor in a state where the imagewise exposed lithographic printing plate precursor is immersed in a developing tank holding an aqueous solution having pH of 8.5 to 10.8 and containing a low molecular weight hydroxycarboxylate ion, a pH buffer agent and a surfactant with circulation of the aqueous solution between the developing tank and an external tank provided outside a processing path line including the developing tank so as to keep constant a liquid level of the aqueous solution in the developing tank.