Abstract: A disk apparatus composed of a disk recording system includes a disk recording medium divided into a plurality of regions in a track direction; a data compressor for compressing the data in terms of time, a recording data delaying apparatus for rearranging the compressed data in time series, a data compounding apparatus for compounding the respective channels into one data a data recording apparatus for recording on the disk recording medium the compounded data; and a data reproducing system including a data reproducing apparatus for reproducing compressed data recorded on the disk recording medium; a data separating apparatus for separating for each channel the reproduced data; a reproducing data delaying apparatus for adjusting the timing of the data of each channel; a data expander for expanding the compressed data of a plurality of channels; an apparatus for compressing in terms of time the data of each channel of signals of a plurality of channels; and separating, recording in a track direction the data