A disk apparatus (10) includes an optical pick-up (12) and a DSP (28), and irradiates a laser beam onto a recording surface of a disk recording medium (100) by the optical pick-up. In a case that a time period (access time period) required for a seek is shorter than a time period (changing time period) required for the number of rotations, the DSP does not simultaneously perform a change of the number of rotations and the seek. To the contrary, the DSP delays the seek by |access time period-changing time period|, and performs a recording and a reproduction after the change of the number of rotation is ended.