A process cartridge remanufacturing method including the steps of: separating photosensitive drum and developing units; dismounting a first side cover member; a dismounting a first gear group from a first bearing member; dismounting a supporting member from the first bearing member; dismounting a second gear group from the first bearing member; dismounting the first bearing member; dismounting a developing roller; dismounting a developing blade; filling a developer into a developer accommodating portion; mounting the developing blade; mounting the developing roller; mounting the second gear group, mounting the supporting member; mounting the first gear group; mounting the first side cover member; and rotatably connecting the photosensitive drum and developing units.