To instantaneously and easily divide a file when dividing the file recorded on a tape.

The file recorded on a tape 101 is expressed with a recording start position and a recording end position. When dividing the file into two, the file from the recording start position to just before a dividing position is defined as a new file 301a and the file from the dividing position to the recording end position is defined as a new file 301b so that the file can be divided. Thus, the file recorded on the tape can be instantaneously and easily divided.