PURPOSE: To prevent such problems as photographic fog, irregular density, or thin density by forming a developer quantity regulating member into a double structure having a rubber elastic layer on a support layer made of a metal thin plate, and specifying the thickness of the rubber elastic layer.

CONSTITUTION: An elastic blade 3 serving as a developer quantity regulating member is pressed into face contact with the outer surface of a developing roller 2, and the tip of the elastic blade 3 is located upstream of the contact section in the rotating direction of the developing roller 2. The elastic blade 3 integrally molded with a rubber elastic body 3b, e.g. HTV rubber, thermoplastic urethane rubber, liquid nitrile butadiene rubber, liquid silicone rubber (LTV, RTV), their denatured objects, and blended objects, on a metal elastic thin plate 3a made of SUS or phosphor bronze. The thickness of the rubber elastic layer 3b is set to 0.2mm or above and nine times the thickness of the support layer 3a or below, thus the hardness of the contact face of the elastic blade 3 with the developing roller 2 is suppressed low.