In a controller of a tape drive, when an error recovery section cannot recover an error detected by an error detecting section, an error-report generation section generates an error report, an error-information acquisition section acquires error information of the tape drive and a cartridge loaded in the tape drive, an error-information exchange section acquires pieces of error information of other tape drives and cartridges loaded in these other tape drives, an error-factor judging section judges whether the error is attributable to the tape drive or the cartridge based on these pieces of error information, an error-report update section updates the error report in accordance with the result of this judgment, and an error-report output section outputs the error report thus updated to a host.