IMAGE FORMING DEVICE

PURPOSE:To improve the reliability of development replacement by a user by making a part for pressing a development unit compatible with the shape of an acting point where a leaf spring is pressing the developing unit. CONSTITUTION:The developing unit 1 has the shape engaging the guide part 11 of an upper surface cover 9 with the insertion guide 7 of the unit 1 provided in a device housing body 6, is held by a developing unit insersion guide 4 attached to the housing 6 and is pressed toward a photo receptor drum 3 with the prescribed force through a projecting part 10 by the two leaf springs 5 attached to the guide 4 to realize conditions for developing image information. In this case, when the projection part 10 on the rear surface of the unit 1 moves onto the leaf springs 5 and, further, fits into the groove, click is caused; a user thereby ensures through hands that the unit 1 is inserted to the prescribed position, and the reliability of the replacement of the unit 1 by the user can be improved.