A seek control unit moves a head to the vicinity of a target track of a storage medium by coarse control, then switches it to fine control, and positions the head to the target track. A rotation disturbance compensation control unit applies a rotation disturbance vibration detection signal based on acceleration velocity sensors to the seek control unit as a compensation signal so as to cancel out rotation disturbance vibration components. A compensation control switching unit sets the rotation disturbance compensation control unit to be either on or off and, when a coarse seek error in which it is out of a fine switch error range upon coarse control by the seek control unit is finished is determined, switches the rotation disturbance compensation control unit to an opposite setting state and causes the seek control unit to perform seek again.