PURPOSE: To always maintain radiation power to the optimum value by detecting temperature of a laser diode and correcting deviation from the optimum value of the radiation power based on the temperature dependency of laser diode using such detected signal.

CONSTITUTION: A controller 16 fetches a current temperature T of a laser diode. Next, the controller 16 obtains a difference between the current temperature input and a predetermined reference temperature and calculates a correction value of the optimum recording laser power value by multiplying such difference with a correction coefficient. The correction coefficient can be obtained from laser waveform varying characteristic for laser diode temperature and optimum recording laser power value varying characteristic for the waveform. The obtained correction value of the optimum recording laser power value is outputted to a recording amplifier 4 as a recording laser power control signal (m) from the controller 16. As a result, the recording amplifier 4 outputs a recording signal (EFM)C having the amplitude depending on the recording laser power control signal m to a pickup 6 via a playback/record selection switch 8.