Patent attributes
The present invention provides a developer cartridge detachably attachable to a casing of an image carrier unit, includes a developing roller and a first rotation body that rotates the developing roller by coupling to a second rotation body provided in an image forming apparatus body with the developer cartridge attached in the casing. The first rotation body is configured to advance and retract with respect to a side wall of the casing which extends along an attachment/detachment direction of the developer cartridge, and is normally urged in an advance direction. A downstream end portion of the first rotation body in the advance direction is arranged downstream in the advance direction from an upstream end of the side wall in the advance direction with the developer cartridge attached in the casing.
