An image forming apparatus has a photosensitive drum (2), a transfer roller (5) above photosensitive drum (2), a transport line (14) that passes between photosensitive drum (2) and the transfer roller (5), a cleaning unit (6) below the transport line (14) and downstream of the photosensitive drum (2), and provided with a cleaning blade (11) and a polishing roller (10) to polish a surface of photosensitive drum (2), and rotation-direction selector (21) to selectively change a rotation direction of the polishing roller (10). The polishing roller (10) is above the cleaning blade (11) and rotationally upstream of photosensitive drum (2) relative to the cleaning blade (11). The rotation-direction selector (21) allows the polishing roller (10) to rotate in the same direction as the photosensitive drum (2) during a polishing mode for polishing the surface of photosensitive drum (2), and in a reverse direction at other times.