Data management method for magnetic tape and magnetic tape storage device

PURPOSE:To shorten access time at the time of updating and referring to directory information in a method managing data in a magnetic tape. CONSTITUTION:At the time of accessing data in the magnetic tape 31 packed into a magnetic tape storage device 20, a data group being the object of access is processed and directory information of the magnetic tape is recorded in an area with the area near a place to which a magnetic tape head is positioned as a directory information area in the magnetic tape 31. A directory information storage area storing directory information of the magnetic tape 31 is provided in the magnetic tape storage device 20. When data in the magnetic tape 31 packed in the magnetic tape storage device is accessed, the data group being the object of access is processed, and directory information of the magnetic tape is recorded in the directory information storage in the magnetic tape storage device 20 by the termination of the processing of the data group.