system differs between when data is read from the optical disk 50 and when data is written thereto during reading the ld 21 operates in dc mode therefore high speed signal transmission does not take place as a result the signal is hardly affected by the transmission characteristic of the flexible transmission line 40 during writing however the ld 21 operates in pulsed mode as a result a high speed signal is transmitted the pulse signal fed to the power monitoring circuit 24 is fast therefore the ic output signal thereof is affected by the transmission characteristic of the flexible transmission line 40 fig5 is a diagram illustrating an example of writing waveform depending on the transmission characteristic of the transmission line 40 ringing may occur in the pulse waveform as illustrated in fig5 this makes it difficult to accurately read the power level of the written portion mark portion of the optical disk 50 or unwritten portion space portion of the optical disk 50 this is the reason why the output resistance and drive current have to be controlled different adjustment procedures are used depending on whether ringing in the signal waveform is caused by a large resonance q value of the flexible transmission line 40 or insufficient current driving capability of the ic output if the flexible transmission line 40 has a large resonance q value the optical pickup is controlled so that the output resistance is increased if the drive current is insufficient the optical pickup is controlled so that the current driving capability is increased fig6 is a diagram illustrating an example of writing waveform after adjustment according to the present embodiment as illustrated in fig6 this adjustment provides a waveform less affected by the transmission characteristic of the flexible.