To prevent the deterioration of resistance to printing and contamination by water-ink balance even when cleaner is used upon printing by a method wherein a light-sensitive lithographic printing plate is provided with an aluminum substrate, anodized and processed by polyvinyl phosphonic acid aqueous solution having a specified pH of lower.

The concentration of polyvinyl phosphonic acid in water solution, used for polyvinyl phosphonic acid water solution treatment after anodizing treatment, is 0.01-10 wt.% or preferably 0.1-5 wt.% and, further, 0.2-2.5 wt.% is the optimum. Any acid can be used to make the pH value of water solution so as to be 1.5 or less and strong acid, such as sulfuric acid, nitric acid, hydrochloric acid or the like, for example, or the salts of these acids can be employed. The temperature of the water solution treatment is preferably 10-70°C or further preferably 30-60°C while the water solution treatment, dipping the substrate of aluminum into the water solution for preferably 0.5-40 sec and more preferably or optimally for 1-20 sec, is proper.