A process cartridge remanufacturing method including: detaching first and second covers, at one and the other longitudinal ends of a process cartridge, from drum and developing frames; detaching a drum supporting member from the drum frame; separating the developing and drum frames; 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 a photosensitive drum to a drum frame; securing the drum frame and the developing frame by a first cover; securing the drum and developing frames by a second cover; temporarily mounting a drum supporting member to support the photosensitive; and mounting the drum supporting member and the second cover to the drum frame by mounting a fixation member to a mounting hole provided in the second cover by using the screw.