An image forming apparatus which reduces abrasion of a photosensitive drum caused by a rotary brush such as an charging brush for electrically charging the surface of a photosensitive drum or a cleaning brush for cleaning the surface of a photosensitive drum. The rotary brush is in contact with the photosensitive drum. During the period of charging the photosensitive drum or cleaning its surface, the rotary brush is rotated in a first mode in which the brush rotates rubbing and sliding the surface of the photosensitive drum, and during other periods, in a second mode in which the brush is rotated passively as driven by rotation of the photosensitive drum. Abrasion of the photosensitive drum is reduced by properly controlling the width of contact between the rotary brush and photosensitive drum and the amount of push for pressing the brush against the photosensitive drum.