A tape device includes a storage unit, a measuring unit, a calculating unit, and an updating unit. The storage unit stores management information in which an identifier of a medium and a data volume further recordable on the medium are in association with each other. The measuring unit measures a data volume written in the medium or a data volume read out of the medium. The calculating unit calculates a data volume recorded in the medium from a total of the data volume measured by the measuring unit, acquires a recorded medium length, and calculates the data volume further recordable on the medium based on the data volume recorded in the medium and the recorded medium length. The updating unit updates the management information stored in the storage unit with the data volume further recordable on the medium which is calculated by the calculating unit.