PURPOSE: To easily discriminate a latent image with the naked eye at the time of exposure, and to obtain a block material which is excellent in the visibility of an image, by laminating successively a light discoloring colored layer containing a high polymer binding material having developer solubility or swelling property, and dyestuff which is brought to light discoloring by the active radiant ray of an ultraviolet part or a visible part, a photosensitive layer, and a supporting body.

CONSTITUTION: A colored layer containing a high polymer binding material and a light discoloring dyestuff is provided on a photosensitive layer. The light discoloring dyestuff is selected from dyestuff having in a molecule at least one kind of structures selected from groups of azo, azomethyn, triphenylmethane, xanthene, oxazine, naphthol, and anthraquinone. As for the high polymer binding material, a high polymer substance which has developer solubility or swelling property and good compatibility to the light discoloring dyestuff, and also, coupled to the photosensitive layer provided under the light discoloring colored layer concerned is used. When the dyestuff is selected, an image part which is brought to light discoloring at the time of exposure is recolored by elution and drying, and an image being faithful to an original picture can be formed on the photosensitive layer.