PURPOSE: To detect the fault of the 1st detecting means, etc., which may result in the destruction of the content of an optical recording medium to stop the light emission of an optical outputting means by monitoring the output signal of a 1st detecting means by means of a 2nd detecting means while an optical output controller makes reproducing or recording.

CONSTITUTION: Fault of a photodiode 12 and current-voltage conversion circuit 20 in an optical output control circuit 15 and disconnection of the signal line for output light monitoring signal between the diode 12 and circuit 20 are detected by monitoring a voltage signal Ve while the reproduced optical output is ON and monitoring the presence/absence of emitter currents of transistors 23 and 24 while the reproduced optical output is OFF. Then the power supply to a semiconductor laser 6, the photodiode 12, and the circuit 15 is disconnected so as to surely stop the light emission of the laser. Therefore, destruction of the information recorded on an optical disk can be prevented surely.