PURPOSE: To simplify an installing work of a charger, by providing a butt member which press-contacts with a photosensitive drum supporting body, on a charger body, so that a space between a discharge line of the charger and a photosensitive drum is always constant.

CONSTITUTION: On a charger installing side frame 1a, a receiving member 15 is provided so that it is capable of freely executing its opposed approaching and separating motions against a photosensitive drum 3, and also the opposed approaching motion against the photosensitive drum 3 is energized and maintained by a spring 17. On this receiving member 15, a charger body 10a is provided so as to be freely attachable and detachable, and also on the charger body 10a, a butt member 25 is provided so as to press-contact with a photosensitive drum supporting body 28, therefore, a space l4 between the photosensitive drum 3 and a discharge line 10b can be made constant at all times by moving up and down the butt member 25 along a long groove 26, adjusting it, setting its height to a prescribed value in advance, and installing it.