A manufacturing method for manufacturing an image bearing unit from a cartridge, the cartridge including: an image bearing member; a frame including a first engaged portion; a supporting member including a fixed portion fixed to the frame, the supporting member including a bearing portion that supports the image bearing member, the supporting member including a second engaged portion opposed to the first engaged portion, and the image bearing member being supported by the bearing portion rotatably around an axis; and a developing unit including an engaging portion (26a, 26b), the engaging portion (26a, 26b) engaging with the first engaged portion and the second engaged portion such that the developing unit being swingably coupled to the frame, the manufacturing method comprising: a dividing step for dividing the supporting member into a first divided portion including the fixed portion and a second divided portion including the second engaged portion; a divided-portion detaching step for detaching the second divided portion from the frame; and a separating step for detaching the engaging portion (26a, 26b) from the first engaged portion and separating the developing unit from the frame. the cartridge including: an image bearing member; a frame including a first engaged portion; a supporting member including a fixed portion fixed to the frame, the supporting member including a bearing portion that supports the image bearing member, the supporting member including a second engaged portion opposed to the first engaged portion, and the image bearing member being supported by the bearing portion rotatably around an axis; and a developing unit including an engaging portion (26a, 26b), the engaging portion (26a, 26b) engaging with the first engaged portion and the second engaged portion such that the developing unit being swingably coupled to the frame, an image bearing member; a frame including a first engaged portion; a supporting member including a fixed portion fixed to the frame, the supporting member including a bearing portion that supports the image bearing member, the supporting member including a second engaged portion opposed to the first engaged portion, and the image bearing member being supported by the bearing portion rotatably around an axis; and a developing unit including an engaging portion (26a, 26b), the engaging portion (26a, 26b) engaging with the first engaged portion and the second engaged portion such that the developing unit being swingably coupled to the frame, the manufacturing method comprising: a dividing step for dividing the supporting member into a first divided portion including the fixed portion and a second divided portion including the second engaged portion; a divided-portion detaching step for detaching the second divided portion from the frame; and a separating step for detaching the engaging portion (26a, 26b) from the first engaged portion and separating the developing unit from the frame. a dividing step for dividing the supporting member into a first divided portion including the fixed portion and a second divided portion including the second engaged portion; a divided-portion detaching step for detaching the second divided portion from the frame; and a separating step for detaching the engaging portion (26a, 26b) from the first engaged portion and separating the developing unit from the frame.