A tape library comprises: a plurality of tape media; a plurality of slots in which the plurality of tape media are respectively stored; a drive in which a tape medium extracted from any of the plurality of slots is set and which performs tape reading or writing in respect of this tape medium; and a controller by which a tape medium is extracted from a designated slot of these plurality of slots and set in the drive. The host computer comprises: a plurality of virtual computers; a first storage region in which is stored slot allocation information expressing which slot is allocated to which virtual computer; and an access control unit that specifies the slot allocated to a first virtual computer, of the plurality of the virtual computers, from the slot allocation information, and restricts access from the first virtual computer to the tape medium in the specified slot.