An image forming apparatus includes a charging device for charging a photosensitive element having a moving surface, by bringing a charging roller, to which voltage is applied, into pressure-contact with the photosensitive element, wherein to the charging member there is applied voltage for forming an electric field such that toner adhered to the charging roller surface at a non-image forming area is oriented towards the photosensitive element. The image forming apparatus is provided with pressure contact force modifying means for making the pressure contact force of the charging roller against the photosensitive element at the non-image forming area greater than that at an image forming area.