A process cartridge detachably mountable to a main assembly of an image forming apparatus, wherein the main assembly of the electrophotographic image forming apparatus is provided with a detecting device for detecting existence of the process cartridge, the process cartridge includes an electrophotographic photosensitive member; a first frame for supporting the electrophotographic photosensitive member; a developing mechanism for developing a latent image formed on the electrophotographic photosensitive member; a second frame for supporting the developing mechanism and rotatably coupled on the first frame; a member to be detected, provided on an upper surface of the first frame and extended bridging between the first frame and the second frame, wherein the member to be detected is capable of being detected by the detecting device to notify mounting of the process cartridge to the main assembly of the electrophotographic image forming apparatus when the process cartridge is mounted to the main assembly of the electrophotographic image forming apparatus.