PURPOSE: To enable efficient operation of attaching and detaching each process apparatus to and from a process cartridge by attaching a member engaging with a developing device to a member held in the process cartridge and positioning and holding an electrostatic charger cooperatively with positioning of the developing device.

CONSTITUTION: A cartridge 17 can be drawn from the body of a device simply by pulling a handle attached to the front of the cartridge. When a positioning lever 55 of a developing device is rotated clockwise, the developing device 5 retreats by turning around a shaft 58 by own weight and the curved edge 5a of the device 5 is disengaged from a lever 51. A released member 22 for holding an electrostatic charger is turned counterclockwise and is leaned on the inside wall of the cartridge 17. A press plate 66 is then removed and a drum 3 is removed in an arrow E direction to end the removal. The attaching operation is accomplished by attaching the drum 3 by means of a U member 65 and the plate 66, then turning clockwise the member 22, turning counterclockwise the device 5, and inserting the cartridge 17 in which the respective apparatus are positioned held into the body of the device.