A recording/reproducing device includes a laser and a laser drive carried by a pickup having a drive for movement. A control controls the drives to irradiate the recording medium with laser pulse sequences forming recording marks having recording mark lengths between a predetermined and maximum lengths, a top section, a last section including a cooling period, and an intermediate period. Heat of mark front edges is controlled by recording parameters for top sections that are classified according to recording mark lengths and recording parameters of the first through the maximum recording mark lengths are classified into a same group. Heat of mark rear edges is controlled by cooling start positions for cooling periods classified according to recording mark lengths. Cooling start positions for a second predetermined mark length through the maximum mark length are classified into a same group. The second mark length is longer than the first mark length.