A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus. The main assembly includes an opening, a cover movable between open and closed positions, and a main assembly electrical contact. The cartridge includes a photosensitive drum; a memory element for storing cartridge; a cartridge contact electrically connected with the memory element being electrically connectable to the main assembly contact when the cover is moved from the open to the closed position after cartridge mounting; a first engaging portion for engaging a main assembly supporting member to position the supporting member with respect to a longitudinal direction of the cartridge before the cover is moved from the open position, and a second engaging portion for engaging the supporting member which moves in interrelation with a movement of the cover when the cover is moved from the open toward the closed position after cartridge mounting and for positioning the supporting member in a direction crossing the longitudinal direction before the main assembly contact is electrically connected with the cartridge contact.