An image forming apparatus includes a photosensitive medium to be charged with a predetermined potential by a charging member, an exposing unit to expose the photosensitive medium to vary a charging level of the photosensitive medium, a developing unit to form an image for one or more colors on the photosensitive medium, a transfer medium to transfer the image from the photosensitive medium, a cleaning unit to clean the transfer medium, and a controller to control an optical power of the exposing unit to be lower than that during forming of the image when a toner band is applied to lubricate at least one of the cleaning unit and the transfer medium.