An image forming apparatus forms an image on a recording material, and detachably mounts process cartridges having photosensitive drums. The apparatus includes a main assembly, a rotatable openable member, a belt receiving an image or carrying the recording material, supporting members supporting the process cartridges at different levels and movable between drum-contacting and retracted positions, and a connecting member moving the supporting member when the openable members moves to position the supporting member at the drum-contacting position when the openable member is closed, and position the supporting member at the retracted position when the openable member is opened, and including a shaft whose axis crosses the openable member rotational axis, first connecting portions rotatably connected with respective supporting members, and a second connecting portion engaging the openable member and fixed to the shaft closer to the openable member than the first connecting portions are fixed to the shaft.