A controller in a hard disk serving as a data storage device stores a license including a content key for decrypting encrypted content data E and others in a secure data storage portion. The license is managed in the secure data storage portion in accordance with a LBA, and the LBA for storing the license, which is being processed for transmission, is stored as a log in a log memory of the secure data storage portion. When a failure occurs during the transmission processing, the license, which was being processed for transmission, is specified based on the LBA stored in the log memory.