PURPOSE: To obtain a late material for lithographic printing of good rust preventiveness and superior hydrophilicity and surface hardness and good printing resistance by forming mixed layers of specific Cr and oxide of Cr on the surface of an iron material by a specific electrolytic method, and forming a photosensitive material contg. a diazo resin, etc. on this layer.

CONSTITUTION: A pretreatment is applied on the surface of an iron plate, a steel plate, etc., by using electrolyte contg. chromic acid anhydride and nitric acid, with said iron material as cathode, after which the electrolysis of a regular treatment is accomplished by using the 2nd electrolyte contg. chromic acid anhydride, boric acid, NH4F, and Ba(NO3)2, with the pretreatd iron material as anode, whereby a bsse material of which the surface layer consists of cracks 1, holes 2, chromic oxide (contg. bivalent, trivalent, hexavalent Cr) 3, and Cr crystal 4, and part of the Cr crystal 4 is exposed on the surface is made. A printing plate material provided with a photosensitive layer contg. a diazo resin on the surface of such base material is made. The plate for lithograhic printing having excellent adhesive power between the base material and the photosensitive layer, good rust preventive power and water retention characteristic and superior durability and print resistance is obtained.