A remanufacturing method for remanufacturing a second developing device from a first developing device, the first developing device including a frame provided with a developer accommodating chamber for accommodating a developer (TY, TM, TC, TK), the frame having an opening for communicating the developer accommodating chamber with the outside of the frame; and a first cap member configured to seal the opening, the first cap member being adhesively bonded to a first region of the frame with a first adhesive capable of dissolving the frame, and the remanufacturing method being characterized by comprising: a removing step of removing the first cap member from the first region, to which the first cap member is adhesively bonded, such that the first region remains on the frame and a rough surface is formed in the first region; a filling step of filling the developer accommodating chamber with the developer (TY, TM, TC, TK); and a sealing step of bonding a second cap member different from the first cap member to a second region of the frame different from the first region to seal the opening with the second cap member, wherein the second region is located closer to the opening than the first region so as to be located on a radially inner side of the opening of the first region on an outer surface of the frame. the first developing device including a frame provided with a developer accommodating chamber for accommodating a developer (TY, TM, TC, TK), the frame having an opening for communicating the developer accommodating chamber with the outside of the frame; and a first cap member configured to seal the opening, the first cap member being adhesively bonded to a first region of the frame with a first adhesive capable of dissolving the frame, and the remanufacturing method being characterized by comprising: a removing step of removing the first cap member from the first region, to which the first cap member is adhesively bonded, such that the first region remains on the frame and a rough surface is formed in the first region; a filling step of filling the developer accommodating chamber with the developer (TY, TM, TC, TK); and a sealing step of bonding a second cap member different from the first cap member to a second region of the frame different from the first region to seal the opening with the second cap member, wherein the second region is located closer to the opening than the first region so as to be located on a radially inner side of the opening of the first region on an outer surface of the frame. a removing step of removing the first cap member from the first region, to which the first cap member is adhesively bonded, such that the first region remains on the frame and a rough surface is formed in the first region; a filling step of filling the developer accommodating chamber with the developer (TY, TM, TC, TK); and a sealing step of bonding a second cap member different from the first cap member to a second region of the frame different from the first region to seal the opening with the second cap member, wherein the second region is located closer to the opening than the first region so as to be located on a radially inner side of the opening of the first region on an outer surface of the frame.