There are provided a disc tray, a traverse unit, and a main chassis unit. The main chassis unit has a main chassis, which has, as observed when the traverse unit is in a stand-by position, a latch portion that engages with a projection portion of a sub rack and a stopper member that restricts the movement of the cam slider. The stopper member has a rotary shaft in the shape of a circular column, a lever portion which the projection portion makes contact, and a lock portion that makes contact with the cam slider and thereby restricts the sliding movement of the cam slider.