Means (101a) for evaluating positional control deviation and means (102a) for outputting a corrective signal, this being a set of signals with kick and brake functions, to an actuator (10) on the basis of the evaluation result are provided. Although control deviation may increase due to external shock or vibration acting on the disc device or when a disc having eccentricity, wobble, or another physical deformity is reproduced, the control deviation is suppressed without loss of control stability, and stable recording and reproducing is always possible.