PURPOSE: To suppress the degradation in photosensitivity by addition of a pigment and to decrease the exposure of a crosslinking reaction by incorporating methylene blow into the compsn. contg. a specific water-soluble acrylic copolymer, pigment and water-soluble diazo resin.

CONSTITUTION: The methylene blue is incorporated into the resin compsn. contg. the water-soluble acrylic copolymer contg. 40 to 90wt.% 2-hydroxyethyl methacrylate, the pigment and the water-soluble diazo resin. The water-soluble acrylic copolymer is photocrosslinked by the water-soluble diazo resin and the photoirradiated part is cured with this photosensitive resin compsn. The mechanism of the photocrosslinking is such that the diazonium groups generate radicals by photodecomposition and that the radicals withdraw hydrogen atoms from the polymers to form the polymer radicals and that the crosslinked structure is formed by the bond of these radicals to each other or the bond thereof with the diazo residues. Then, the polymers having the active hydrogen atoms are more liable to crosslink and above all, the polymers having alcoholic hydroxyl groups have the higher activity and are liable to crosslink.