Embodiments of the invention decrease bending vibrations and torsional vibrations of a voice coil generated by off-plane vibrational forces on the voice coil to reduce noise and to enable a large capacity. In one embodiment, a rotating disk type storage unit comprises a rotating disk recording medium, a head that moves radially relative to the rotating disk recording medium to perform recording or reproduction, a turnable actuator having mounted on one side thereof the head, and a voice coil motor to drive the actuator. The voice coil motor comprises a voice coil mounted on the other side end of the actuator, and a magnet arranged in opposition to the voice coil. A magnet outer periphery of the magnet disposed distant from an actuator turning center is formed to be arcuately concave in shape, and the concave-shaped outer periphery intersects the voice coil.