To make a printing plate by executing exposure treatment corresponding to digital image information without using a high output laser beam source.

A lithographic printing original plate having an image forming layer including titanium dioxide or zinc oxides and a supporting body is irradiated with a beam in which the wavelength of the maximum spectral peak is 150 to 350 nm and which corresponds to image data from a DMD. The lithographic printing plate is made by changing the titanium dioxide or the zinc oxides at an exposure part to a hydrophilic state.