An image forming apparatus having an insulated member disposed adjacent to a photosensitive member, a scanner exposing an image on the photosensitive member in a direction perpendicular to the direction of movement of the insulated member while voltage is applied between the photosensitive member and the insulated member so as to provide a charge on the insulated member surface corresponding to the optical exposure image. The exposure position exposed by the scanner is changed in the direction of movement of the image-bearing member for each scan.