A content playback device of the present invention includes a playback unit 200 operable to play back a content; a normal storage unit 250 that is not tamper-resistant; a secure storage unit 350 that is tamper-resistant; a first control sub-unit 230 that writes playback records indicating elapsed playback time of the content into the normal storage unit one by one at regular time intervals; and a second control sub-unit 330 that (i) writes monitoring records with respect to the playback records into the secure storage unit 350 one by one at irregular time intervals and (ii) determines that the playback records stored in the normal storage unit 250 have not been tampered with if a prescribed relation is satisfied between a specific time point obtained according to a latest one of the monitoring records and one of the playback records corresponding to the specific time point.