PURPOSE: To prevent a remote control operation by a third party by counting the nonconformity of a transmitting code and a password code and rejecting the reception of the transmitting code sent afterward when the nonconformity is more than prescribed times.

CONSTITUTION: When the transmitting code sent from a transmitting part does not coincide with the password code, a system control 2 actuates a message synthesizer 8, controls so as to send an error message to a telephone line 1 and counts the number of times of errors. When this count value is counted the prescribed times, the effect is displayed on a LED 9. The system controller 2 controls so as to reject the reception even when the transmitting code sent after the transmitting code sent erroneously coincides with the password code. Thus, the remote control operation from the third party who does not know the password code is prevented, a secret can be kept and a dangerous remote control can be prevented.