A method of remanufacturing a process cartridge detachably attachable to an image forming apparatus main body, the method including: separating a first side cover from a developing unit and a photosensitive member unit; separating the photosensitive member unit from the developing unit by deforming a second side cover in a state where the second side cover and the developing unit are fixed to each other; detaching an electrophotographic photosensitive drum from the photosensitive member unit; attaching one of the electrophotographic photosensitive drum and a new photosensitive drum; engaging the developing unit with the second side cover that is fixed to the developing unit; and engaging the first side cover with respective end portions of the developing unit and the photosensitive member unit.