PURPOSE: To prevent the generation of a jitter phenomenon, by irradiating a photodetector provided within a scan region of the laser beam with a laser beam having larger power than that of a recording mode and setting the timing for start of recording using the laser beam based on the signal delivered from the photodetector.

CONSTITUTION: A photodetector 8 is set within a scan region of a laser beam, and the voltage detected by the detector 8 is amplified by an amplifier 10 and compared with the comparison voltage VL through a voltage comparator 11. Then a pulse signal A is delivered by a 1-shot multi 12 when the voltage is changed to a high level from a low level. This signal A is applied to an FF14 of a recording circuit as a recording start signal, and the FF14 is reset with the output of a counter 13. The output Q' of the FF14 is applied to a voltage controller 15, and the output Q' is synthesized with a picture signal sent from a terminal C and delivered only when the output Q' is set at an H level. Then the output of the controller 15 is applied to a driver 2-2 of an optical modulator to set the laser beam recording start timing. This prevents generation of jitter.