Patent ID: 8768215

Claim:
An image forming apparatus comprising: an image forming unit, including a rotatably supported image bearing member; a developing unit including a first rotatable developer carrying member for developing an electrostatic latent image formed on the image bearing member and a second rotatable developer carrying member for developing the electrostatic latent image formed on the image bearing member, first gap regulating member, provided at both ends of the first rotatable developer carrying member, for regulating a gap between the image bearing member and the first rotatable developer carrying member; second gap regulating member, provided at both ends of the second rotatable developer carrying member, for regulating a gap between the image bearing member and the second rotatable developer carrying member; urging means for urging said developing unit toward said image forming unit; and a positioning unit for positioning said developing unit relative to said image forming unit, wherein said positioning unit includes a preventing portion for preventing, while permitting movement of said developing unit in a circumferential direction of the image bearing member at a first longitudinal end of said developing unit, movement of said developing unit in the circumferential direction of the image bearing member at a second longitudinal end of said developing unit.