A power control system controls power of light emitted from a light source to a recording medium. The light having a first power is used to erase previous information from the recording medium and the light having a second power is used to record information in the recording medium in a recording operation. The power control system includes a detecting unit for detecting reflected light from the recording medium when the light source emits the light having the first power to erase the information from the recording medium. The detecting unit outputs a reflection signal corresponding to the reflected light. The power control system further has a control unit for controlling the first power of the light emitted from the light source so that a level of the reflection signal output from the detecting means is controlled at a predetermined target level.