PURPOSE: To stably read and write data by controlling a shortest pit and a shortest gap pulse width with a recording pulse width control means and controlling other pulse widths with another recording pulse width control means.

CONSTITUTION: Reproduced data 10 and recorded pulses are inputted to terminals 9 and 7, respectively. A recording pulse width control means 2 controls the pulse widths of a shortest pit and a shortest gap among recording pulses and a recording pulse width control means 3 increases/decreases total pulse widths uniformly and performs the control. A recording power control means 4 controls the power at the time of recording, a semiconductor laser driving circuit 5 drives a semiconductor laser 6 by the outputs of the means 3 and 4. A pulse width detecting means 1 detects the pit sections of the reproduced data 10 or the pulse width between pit sections.