Abstract: An image forming apparatus includes a casing, a mirror, and an adjustment device for adjusting a position of the mirror. The adjustment device is disposed within the casing and includes a frame, a plate, a connection unit, a first adjustment unit, a connection element, and a first adjustment element. The frame includes a vertical surface and a horizontal surface with a hole therein. The plate is configured to hold the mirror. The connection unit and the adjustment unit are protrudedly disposed on the plate. The connection element connects the plate to the vertical surface of the frame. The first adjustment unit includes a first groove. The first adjustment element couples with the hole through the first groove. By adjusting the position of the first adjustment element in the first groove, a position of the plate relative to the frame is adjusted.