An operation to recycle a process cartridge comprising a mechanism for returning waste toner not used in image formation from an image carrier to a developing device can be performed easily, and situations in which an image creating element that has not reached the end of its life is discarded together with an image creating element that has reached the end of its life, making reuse thereof impossible, can be suppressed. The process cartridge comprises an image carrier unit including an image carrier, a developer carrier unit including developing means, and a waste toner conveyance unit having a built-in waste toner conveyance mechanism. These three units are assembled detachably.