An external storage medium management system takes into account the maintenance of data security in case an external storage medium has been taken out on emergency. It comprises an external storage medium device and an enclosure device, which is connected to a host side device and which accommodates the external storage medium device, the external storage medium device reports the result of authentication to the enclosure device in case authentication operation is done. On detection of extraction of the external storage medium device from the enclosure device, the external storage medium device of inhibits access to retained data and allows access to the data only in case the authentication in accordance with a preset system has met success. In case the enclosure device also has detected the extraction of the external storage medium device by a medium extraction detection unit, the enclosure device announces the status prevailing at the time of the extraction (authentication coincidence/non-coincidence/authentication data invalid/no authentication data) to the host side.