To provide a printer loading a plate making process that can rewrite a printing plate image on a printing plate in a short period of time, capable of coping with a market need of large-item small-scale production.

The plate making apparatus includes: the printing plate having a charge generating layer formed on a conductive substrate, and a porous surface layer formed of a material having a hydrophobic property on the charge generating layer; a supply means for supplying an electrolysis solution on the surface of the printing plate; and a printing plate image forming means for applying stimulation to the printing plate according to an image signal to generate charge on the charge generating layer, selectively precipitating electrolytes on the printing plate, and forming a printing plate image on the printing plate. The problem is solved by providing the printer capable of forming an ink image on paper using the printing plate.