PURPOSE: To obtain images having less unequal colors by applying microcapsules contg. a silver halide, reducing agent, polymerizable compd., and color materials onto a plastic film which is specified in thickness and heating elongation and contraction rate and is deposited with aluminum by evaporation on the surface.

CONSTITUTION: The plastic film which has ≤75μ thickness and is -5 to +0.5% both longitudinally and transversely in the heating elongation and contraction rate measured in a 120 to 180°C temp. range and is subjected ot the vapor deposition treatment of the aluminum on its surface is used as the base of the photosensitive material. The photosensitive material for heat development formed by applying the microcapsule contg. at least the silver halide, reducing agent, polymerizable compd., and color materials on such plastic film is used. the elongation and contraction of the base are decreased in this way and the adhesion between the microcapsule layer and the base is improved. The unequal colors are thereby decreased.