In a repetitive control device used for processing a servo signal, a memory (7) is used as a delay element for a filter (6), and a filtering process by the filter (6) is carried out using a clock signal that is an integral multiple of an operation frequency of a driving signal. Therefore, the gain can be increased without generating phase rotation with respect to a compensated signal, and high followability can be achieved to fluctuations in the track position which are caused by the shape of a disc such as decentering or surface wobbling, during recording and playback in an optical disc device.