An image forming apparatus includes a photosensitive drum, a rotation supporting unit for rotatably supporting the drum, a charger, an optical image forming unit, a development unit, a transfer unit and a cleaner, which are arranged along the outer circumferential surface of the drum in a rotational direction of the drum, and a rotation resistance adjusting unit for applying a rotation resistance on a region of the drum located outside of the image forming region, and being capable of adjusting a value of the rotation resistance applied on the drum. The development unit includes a development roller abutted to the image forming region of the circumferential surface of the drum and rotated in an opposite direction to the rotating direction of the drum. At least one of the supporting unit, charger, image forming unit, the transfer unit and the cleaner includes a rotation resistance member for applying a rotation resistance on the drum in an opposite direction to a direction of a rotation resistance applied from a development roller to the drum. A value of frictional torque T3 applied from the adjusting unit to the drum is so set that a relationship "T1