A process cartridge is detachably mountable to a main assembly of an electrophotographic image forming apparatus and which is transportable in a state of being mounted to the main assembly of the apparatus. The cartridge includes an electrophotographic photosensitive member, a developing roller for developing an electrostatic latent image formed on the member with a developer, a developer accommodating portion accommodating the developer and having a developer supply opening for permitting passage of the developer to supply the developer to the roller, a sealing member unsealably sealing the opening and a grip member, provided on the sealing member, for being gripped to unseal the opening when the sealing member is removed from the opening. The grip member is movable between a first position where the cartridge can move to a predetermined position in the main assembly to permit transportation of the cartridge when mounted to the main assembly, and a second position where the cartridge is prevented from moving to the predetermined position from the first position when the cartridge is dismounted from the predetermined position.