PURPOSE: To omit a heat treatment stage in an image reversal method and to improve the preservation stability of a resist material by incorporating a block type isocyanate compd. into a photosensitive resin compsn. essentially consisting of an alkaline soluble polymer having a hydroxyl group and a diazonaphthoquinone compd.

CONSTITUTION: The block type isocyanate compd. is incorporated into the photosensitive resin compsn. contg. the alkaline soluble polymer having the hydroxyl group and the diazonaphthoquinone compd. as its essential components. This pattern forming material, subjected to irradiation of high energy beams, generates active isocyanate which reacts with the hydroxyl group of the polymer and suppresses the alkaline solubility of the resist. The heat treatment stage of the fore stage of the stage for irradiating the entire surface with ultraviolet rays in the conventional image reversal method is omitted. Since the block type isocyanate compd. is extremely stable at room temp., the degradation in the preservation stability is prevented.