An electrophotographic image forming apparatus is provided including a body including an opening and a first coupler, a photoreceptor cartridge including a second coupler connected to the first coupler, a first gear connected to the second coupler, and a mounting portion, and attached to or detached from the body through the opening; and a development cartridge including a second gear connected to the first gear and attached or detached from the mounting portion through the opening while the photoreceptor cartridge is mounted in the body.