The present invention includes two side-plates configured to be opposed to each other and to form a frame of a main body of the apparatus, a cartridge with an image bearing member, a moving member configured to support and move the cartridge, a connecting member configured to connect the two side-plates, and a positioning member configured to be held by the connecting member, wherein the moving member, which is movable between the two side-plates, the cartridge is attachable to and detachable from the moving member when the moving member is withdrawn to the outside of the main body of the apparatus, and the cartridge is positioned by the positioning member when the moving member is moved and the cartridge is contained in the main body of the apparatus.