PURPOSE:To lower the maximum temp. of a recording film and to realize a high- density optical recording by increasing the wavelength of light or deviating a focus or reducing an aperture ratio of a lens at the time of erasing recorded information. CONSTITUTION:A optical head 102 converges the light of a laser 108 to a medium 101. The input information is outputted from the laser 108 through a recording generator 105 and an APC 106 at the time of recording. The reflected light from the medium 101 is outputted through a photodetector 109 and an amplifier 110 to a waveform equalizer 111 and an input switch 112 at the time of reproducing the information. Output pulses are introduced to a discriminator 115 and a PLL 114 and the information is outputted from a decoder 117. A comparing discriminator 116 outputs the information of a trial writer 103 to a coder 104 and an input switch 112 switches the output of the amplifier 110 to a waveform shaper 113. The information from the coder 104 and the diacriminator 115 is compared and a trial writing end signal is emitted when the difference decreases to a permissible range. The change in the fluctuation in the sensitivity of the disk, etc., with the lapse of time according to the repetition of recording/erasing is suppressed by this constitution. The control of the shapes of the recording magnetic domains with high accuracy is thus made possible.