An optical disk apparatus has: a laser (14) that outputs light; an optical system that includes an SIL (2) for forming a predetermined sized beam spot on an optical disk (1) using the light from the laser; a detector (26) that detects output power of the laser and generates a laser power detection signal; a laser power control circuit (27) that controls the output power of the laser using the laser power detection signal; a detector (10) that detects a gap length between the optical disk and the SIL and generates a gap detection signal; and a gap control circuit (15) that controls the gap length between the optical disk and the SIL using the gap detection signal. The power control circuit has a gain crossover frequency greater than a gain crossover frequency of the gap control circuit.