An image forming apparatus for forming a developed image includes a developing device for developing an image on an image bearing member, a passage along which the developing device is movable continuously between an inside position where the developing device is inside the apparatus and an outside position where the developing device is at least partly outside the apparatus, a driver for automatically moving the developing device along the passage and one or more pressing members for pressing the developing device toward the image bearing member. The driver includes a driving source and transmission which are operative to move the developing device in response to the opening of a cover which covers an inlet to the passage.