An image forming device includes an electrostatic latent image carrier on which an electrostatic latent image is formed, a main frame which supports the electrostatic latent image carrier, and a developing unit which is inserted removably in the main frame. The developing unit includes a developer carrier which supplies a developer to the electrostatic latent image carrier and a replenish chamber which replenishes the developer to the developer carrier. The image forming device also includes a pressing body which is provided on the main frame and is slidable in a direction along a straight line orthogonal to a rotational center shaft of the electrostatic latent image carrier and a rotational center shaft of the developer carrier, and an operating unit which operates the pressing body to press a bottom surface of the developing unit by sliding the pressing body in a direction of the straight line and to hold the pressing body so that the developer carrier is maintained under a state making contact with the electrostatic latent image carrier.