To easily distinguish the material of base substance for a drum in the case of waste disposal processing or recycling processing for a photoreceptor by displaying a material mark on a part of the surface of a drum-like resin base substance.

In the case of using the substance principally composed of PPS resin, for instance, and having specified volume resistivity by blending specified high conductive carbon black as the material of the base substance for the drum 1; 'PPS' is displayed as the material mark 2 on the surface of the base substance for the drum 1. It is desirable that a place where the material mark is formed is the periphery of an end being the uncoated part of an organic photoreceptor layer which does not directly participate in image-forming on the base substance for the drum 1. The material mark 2 is engraved on a metallic mold and displayed on the outer surface of the base substance at the time of molding. Besides, a method for displaying the material mark by laser marking on a part of the surface of the base substance after molding or a method for sealing and displaying the material mark on a part of the outer surface of the base substance by using eternal ink is adopted.