An electrophotographic image forming apparatus for forming an image on a recording material includes a detachably-mounted cartridge including an electrophotographic photosensitive member, first and second portions-to-be-regulated for regulating rotation of the cartridge when a driving force receiving portion receives a driving force, and a transfer member for transferring a developer image formed on the electrophotographic photosensitive member onto a toner image receiving member. A supporting member is movable between an inside position which is in a main assembly of the apparatus and an outer portion, and a contacting and spacing member is movable relative to the supporting member. In addition, a first regulating portion permits movement of the supporting member between the outer position and the inside position, and a second regulating portion regulates rotation of the cartridge.