PURPOSE: To obtain a low noise reproducing signal by attaining the proper level of a recording signal level due to the difference of linear velocities at the outer and inner peripherals of an optical disk.

CONSTITUTION: The power of a laser beam to irradiate the optical disk at the time of recording is formed by superimposing a low level DC component P1 on a high level pulse-like component P2, the pulse-like component P2 is constant on the outer and inner peripherals of the optical disk and the low level DC component P1 becomes bigger as it is nearer to the outer peripheral. Also, the reproduction of the recording information of the optical disk is executed by irradiating the laser beam of the low level DC component P1.