When setting a recording power for use in recording optical information on a DVD-R, by using any one of sectors provided on the DVD-R as a PCA, whether a predetermined special detected signal is detected or not in the sectors is checked (Step S2), a non-used sector where no special detected signal is detected, of the sectors, is retrieved, based on the check result (Step S3), a mark signal for obtaining the special detected signal is recorded in the retrieved non-used sector (Step S5), a setting signal for setting a recording power is recorded in the non-used sector excluding the area where at least the mark signal is recorded (Step S6), and the recorded setting signal is optically detected to set the recording power (Step S13).