Patent ID: 8099020

Claim:
A developer cartridge that is attachable to and detachable from a developing housing, the developing housing supporting a developer carrier and comprising a drive gear for transmitting a driving force to the developer cartridge, the developer cartridge comprising: a cartridge housing that is configured to accommodate developer, the cartridge housing including: a first housing, and a second housing that is movable with respect to the first housing; an agitation gear that is provided in the cartridge housing and is configured to agitate the developer by the driving force; a transmission gear that is configured to mesh with the agitation gear, the transmission gear meshing with the drive gear when the developer cartridge is installed in the developing housing; and a supporting member that is configured to support the transmission gear movably with respect to the agitation gear while the transmission gear meshes with the agitation gear, wherein the second housing comprises a holding member that is configured to hold the transmission gear at a spaced-apart position in which the transmission gear is spaced apart from the drive gear or release the hold of the transmission gear at the spaced-apart position in accordance with movement of the second housing, the holding member including a projection that is engageable with at least one of the transmission gear and the supporting member.