An optical disk apparatus and control method having a rotation driver configured to rotationally drive an optical disk, a laser diode configured to emit a laser light to be irradiated upon a recording surface of the optical disk, for recording or reproducing information onto the optical disk, and a monitor device configured to monitor the laser light emitted from the laser diode. An intensity of the laser light emitted from the laser diode which is detected by the monitor device is memorized by a memory, a detector detects an abnormal condition of the laser diode, by comparing a present laser light intensity with a previous laser light intensity, and a controller controls a rotating velocity of the optical disk in dependence upon detection of the abnormal condition.