Disclosed are a printing plate material capable of being developed on a printing press and its manufacturing method which comprises the steps of subjecting an aluminum plate to electrolytic surface roughening treatment, subjecting the electrolytic surface roughened aluminum plate to etching treatment in an aqueous alkali solution, subjecting the resulting aluminum plate to anodization treatment, whereby an aluminum support is obtained, and providing on the aluminum support an image formation layer which contains thermoplastic particles and a light-to-heat conversion dye and changes in color due to infrared laser exposure.