PURPOSE: To efficiently perform the rewrite of information in a short time by providing a current setting circuit, and modulating and recording a light beam based on the level of a signal inputted to a light source at the time of performing the erasure of the information.

CONSTITUTION: A current of no modulation from the current setting circuit 10 is inputted to the light source 5, and the information recorded on a medium 19 is erased. At this time, a controller 11 closes switches Sw 3 and 5, and opens a switch Sw 4. And the circuit 10 controls the power of the light beam of the light source 5 so as to go to a prescribed value based on the output of a photoelectric conversion element 4. When an erasure process is completed, the controller 11 opens the switch Sw 5, and holds an input signal to the light source 5. Next, the signal that changes between a level held corresponding to recording information and the level less than that is inputted to the light source 5. Furthermore, the medium 19 is irradiated by a modulated light beam, then, new information is recorded. In such a way, since the preset value of the circuit 10 is modulated in the rewrite of the information, it is performed in a short time.