A process cartridge remanufacturing method including: detaching, at one longitudinal end of a process cartridge, a first cover member from a drum frame and a developing frame; detaching, at the other longitudinal end, a second cover member from the drum frame and the developing frame; detaching a drum supporting member from the drum frame; separating the developing frame and the drum frame; detaching a developing roller from the developing frame; filling a developer containing portion with the developer from a developer supply port provided on the developing frame; mounting a developing roller to a developing frame; mounting, at the one end, a photosensitive drum to a drum frame; securing the drum frame and the developing frame in position at the one end by a first cover member; securing the drum frame and the developing frame in position at the other end by a second cover member; temporarily mounting a drum supporting member to support the photosensitive drum at the other end; and mounting the drum supporting member and the second cover member to the drum frame by mounting a fixation member to a mounting hole provided in the second cover member by using the screw.