A process
cartridge detachably mountable to a main
assembly of an electrophotographic image forming apparatus including an openable member movable between a closing position for n opening and an open position for the opening, a guiding member, a main
assembly positioning portion, and a main
assembly movable member movable in interrelation with the openable member, the
cartridge includes an electrophotographic photosensitive member; process means actable on the photosensitive member; a
cartridge positioning portion, engageable with the main assembly of the apparatus, for positioning the cartridge relative to the main assembly; a cartridge movable member movable by movement of the main assembly movable member, when the cartridge, upon mounting of the cartridge to the main assembly through the opening while being guided by the guiding member, stops at a position upstream, with respect to a cartridge mounting direction, of an
image formation position where the cartridge positioning portion is engaged with the main assembly positioning portion, the cartridge movable member is moved by movement of the main assembly movable member to contact to the guiding member, by which the cartridge movable member receives, from the guiding member, a force for moving the process cartridge toward downstream with respect to the mounting direction.