The present invention provides a data recording method a data recording and/or reproducing apparatus for recording data transmitted from a computer to a magnetic tape. In case a recording head fails to write data (data ID=582) of fragment ID=5 to a track (track 7), then, the data is rewritten to the first fragment (ID=0) of a next track (track 8). Thus, the data can be rewritten not on the track basis but on the fragment basis, which can reduce loss of tape capacity significantly.