It is an object of the present invention to improve a margin to meet good recording quality by conducting a realtime correction of a recording condition of a medium with different recording characteristics for inner and outer circumferences. To accomplish the object, control factors for power and a pulse width are independently detected and corrected using an mT pulse having a length of m′T as a pulse for power control and an nT pulse having a length of n′T as a pulse for pulse width control; more specifically, power correction for mT pulse and pulse width correction for nT pulse are conducted in realtime, wherein a recording pulse stream including the mT pulse and nT pulse is irradiated onto a medium by a recording laser beam as well as pits and spaces formed by irradiation of the recording pulse stream are reproduced by a reproducing laser beam to detect the effects of power and pulse width variations independently.