To prevent duplicate forbidden data from being unfairly recorded or reproduced even under the condition where a correct time cannot be obtained from an internal clock for measuring the hold period within the period for holding duplicate forbidden data.

A timer 14 provides a timing signal at every designated time. A time recording part 15 records the time shown by the internal clock 13 in a non-volatile memory 16 in response to a timing signal provided from the timer 14. A time comparing part 17 compares the time of the internal clock 13 with the time recorded by the time recording part after designated time from the timing signal. A determining part 18 determines whether the operation of the internal clock 13 is normal or not according to the comparison result of the time comparing part 17. When abnormality is transmitted as determination result from the determining part 18, a record reproduction control part 19 limits record and reproduction of duplicate forbidden data to the HDD21.