An optical disc apparatus which realizes high density disc recording using an existing disc and an existing recording signal processor. When recording data on a recordable disc corresponding to an existing first standard, either one of first and second recording signal processors 9 and 10 can be selectively used, so that data recording in the high density recording mode which allows data generated by the second recording signal processor 10 to be recorded on a recordable disc corresponding to the first standard can be performed. As a result, the existing second standard data format can be used with regard to a disc corresponding to the existing first standard, so that recording can be performed at a higher density than when the first standard data format is used for the same disc, thereby increasing recording capacity.