A process cartridge detachably mountable to a main assembly of an image forming apparatus includes an electrophotographic photosensitive member; developing device for developing an electrostatic latent image formed on the electrophotographic photosensitive member with a developer; a developer container for containing the developer, the developer container having an opening for supplying the developer to the developing means; a sealing member for sealing the opening of the developer container; a winding shaft for winding the sealing member, the sealing member being rotatably supported by the developer container; a driving device for applying a driving force to rotate the winding shaft; and drive control device for permitting and preventing transmission of the driving force to the winding shaft, wherein the driving control device permits the transmission in response to insertion of the process cartridge into the main assembly of the image forming apparatus and prevents transmission in response to a predetermined number of rotations of the winding shaft.