A door opening and closing unit is provided for an image forming apparatus. The image forming apparatus includes a main body, and a door rotatably mounted on the main body. The door opening and closing unit includes a door speed control unit coupling the door to the main body that includes a coupling boss; and a guide groove that engages the coupling boss and along which the coupling boss moves as the door rotates relative to the main body; wherein the door speed control unit controls a frictional force between the coupling boss and the guide groove according to a rotating angle of the door relative to the main body to control a rotating speed of the door as the door rotates relative to the main body.