To appropriately set the servo gain of focusing and tracking of a recordable optical disk such as CDR, CDRW.

A servo circuit 24 sets the servo gain based on a FE (focus error) signal obtained at a front end 20 and a TE (tracking error) signal. In that case, a pit detecting circuit 30 detects existence of parts by a signal from the front end 20, when pits do not exist, the servo gain is set to a higher value than the optimum value in which the servo gain is obtained. Thereby, the appropriate servo gain can be set when a part in which pits exist is read.