PURPOSE: To raise an alarm to a user by displaying validity when a remaining period from current time to the end of the validity is within a prescribed period decided in advance by providing a display part to display the validity.

CONSTITUTION: A scramble decoder 4 owns data expressing the validity of reception. On the other hand, a timer part 5 manages the current time. A control microcomputer 6 calculates the remaining period from the present to the end of the validity according to the data read out of the scramble decoder 4 and the current time read out of the timer part 5. In this case, a period to start the display of the remaining period is decided in advance and processed in the microcomputer for control as a software. When the calculated remaining period is out of the prescribed period, the microcomputer 6 for control does not output any signal for display. When the remaining period is within the prescribed period, however, the signals for display are continuously outputted afterwards. Therefore, a display part 7 displays the validity according to the signals for display. The validity of the scramble decoder can be updated by paying an update tariff.