PURPOSE: To eliminate loss time required for a positioning processing at the time of resumption after the travel of a tape stops by transferring written data on the magnetic tape or transferring read data from the magnetic tape with a host device through a data buffer.

CONSTITUTION: After transferred data from the host device 2 is stored in the data buffer 20 on the side of a storage control part 10, the data is transferred to the side of a drive 12 and is written on the magnetic tape 1. After data which is read from the magnetic tape 1 is transferred and stored in the data buffer 20 on the side of the storage control part 10 from the side of the drive 12, it is transferred to the host device 12. When the data buffer 20 becomes temporarily empty while data is transferred from the data buffer 20 at the time of writing to the side of the drive 12, dummy data is transferred to the side of the drive 12 and is written on the magnetic tape 1. Thus, loss time required for the positioning processing at the time of resumption after the travel of the tape 1 stops can be eliminated.