A developing device has a rotatable developer holding cylinder and a developing device box for supporting the developer holding cylinder. The developing device box is freely suspended by a holding device, and pressure is resiliently applied to the cylinder so that the cylinder is maintained at a predetermined close distance with respect to a rotatable image bearing member. The position at which the developing device box is suspended is set to a position at which a force component of the driving force transmitting the rotational movement of the image bearing member to the developer holding cylinder acts in a direction in which the cylinder moves away from the image bearing member.