PURPOSE: To form a recording pit in an optimum shape by varying the irradiation output of a laser beam according to the interval from the time when the preceding formation of the recording pit by an optical head just ended to the time when the formation of the next recording pit started.

CONSTITUTION: An LD control circuit 4 is provided with a divider circuit 41 dividing a reference voltage V0 at a prescribed voltage division ratio, an amplifier 43 amplifying the obtained divided potential and generating a prescribed first recording voltage V1 and the amplifier 42 amplifying the second divided potential obtained in the divider circuit 41 and generating a second recording voltage V2. Further, the circuit 4 is provided with a switch 45 switching the first recording voltage V1 by a second pulse line 27 and the switch 44 switching the second recording voltage V2 by a first pulse line 25. A recording signal 47 is obtained by the outpus of the switches 44, 45 to be supplied to the optical head. Since a disk is preheated by the second pulse line of the first recording voltage V1 for a preheat interval before the recording of the second recording voltage V2 by the first pulse line, the temperature of the disk at the time of starting the recording is adjusted to a required temperature, and the recording by the first pulse line is performed under a stable condition.