On the inner surface of a guide rail (411) having a concave groove, which extends in the vertical direction along a motion path of a disc drive (200) moved by a mover unit (300), a biasing cam (412) having thickened swelling parts (412a) at both ends is so provided as to have the groove width narrowed at both the upper and lower ends. A plate spring (420) which is pressed into contact with a guide surface of the surface of the biasing cam (412) by elastic biasing force is attached integrally to the disc drive (200). At the home position where the disc drive (200) operates and at the position where the disc drive (200) is lifted up, the plate spring (420) is strongly pressed into contact by the swelling parts (412a), and the disc drive (200) can be prevented from being moved by impact or the like from outside during operation. While moving, the pressing force is weakened so that load applied by the mover unit (300) can be reduced.