A transfer unit of an image forming apparatus includes a belt to receive an image developed on a photosensitive medium while rotating in a regular cycle and in contact with an outer circumference of at least one photosensitive medium. A blade arm, which is installed adjacent to the belt, moves to a first position to position a cleaning blade, which is supported by the blade arm, to be in contact with the belt. The cleaning blade is coupled to a pressure unit to bias the cleaning blade towards the belt.