A data storage device includes: a recording medium that has two or more system data recording areas where system data are recorded on a multiple basis, and a user data recording area where user data is recorded; a head that writes and reads data into and from the recording medium; and a system data update control section that causes the head to update the system data on the recording medium. The system data update control section causes the head to record new system data on a multiple basis in another sub-record area that is alternately selected at each update to the new system data over the two or more system data recording areas when each the two or more system data recording areas is divided into two sub-record areas, and read the new system data from the another sub-record area to confirm that the new system data is recorded correctly.