A cartridge that can be detachably installed within an imaging device, which includes a cartridge casing, a photosensitive drum driving assembly located on the casing, and a control mechanism for controlling extension and retraction of a force receiving head in the photosensitive drum driving assembly. The control mechanism includes a control rod, which can rotate around a pivot on the cartridge casing, and a elastic means mounted on the control rod. The cartridge of the invention uses a control mechanism to control extension and retraction of the force receiving head in the photosensitive drum driving assembly, and as a result when the cartridge is removed of the imaging device, the force receiving head does not become stuck by a driving head of the imaging device.