PURPOSE: To provide an image forming device for electrophotographic copiers, recorders, etc. by having a process unit which is so constituted as to permit attaching and detaching of the whole or a part of a photoreceptor as an image carrying body, and image forming means disposed around the same to and from the body of a device.

CONSTITUTION: To mount a process unit U to the body of a device, a cam 19 is rotated integrally with a shaft 23 by turning and shifting an operating lever 24 clockwise by which a leaf spring 18 which is held lifted by the cam 19 is moved downward. When a lower guide 11 for transfer turns downward, a groove 25 is disengaged from a louvered part 26 by which the unit U is unlocked, and a separating belt 12 descends and retreats from the operating position, thus assuming the state of permitting insertion of the unit U. Then the operator pushes and mounts the unit into the prescribed loading position of the body. To remove the unit U from the body, the lever 24 is turned clockwise, by which the unit U is unlocked, and the guide 11 is retreated below the belt 12, and the unit U is easily removed from the body.