An electrophotographic image forming apparatus and a development cartridge are provided. The electrophotographic image forming apparatus includes a body including an opening, a photoreceptor cartridge attached to, or detached from, the body through the opening, a photoconductive drum and a mounting portion, a development cartridge attached to, or detached from, the mounting portion through the opening while the photoreceptor cartridge is mounted in the body, a development roller supplying toner to an electrostatic latent image formed on the photoconductive drum, a cover for opening or closing the opening, and a pressurizing unit fixing the development cartridge to the mounting portion by providing a pressing force to the development cartridge in a direction parallel to a center line connecting centers of the photoconductive drum and development roller while the opening is closed.