PURPOSE: To prevent a remote controller from being malfunctioned, by completing the receiving of a signal of N-bit when a received N+1-th signal exceeds the maximum time taken as a significant signal.

CONSTITUTION: A decoder input 32 might be given to a decoder 10 as a mixed waveform of a remote control signal 30 and a noise 31 due to noise such as optical noise or noise from peripheral electric device at an optical remote control receiving side. The number of counts of a remove control signal of a register at a time t10 in this case reaches 9 (9=N+1), and the processing is kept further until time t11. Moreover, the processing is continued from the time t11 to t12 and when the count number reaches 10, the processing is restored to the start. Since the time between the t10 and t11 is within the permissible time taking a data as 1, the receiving of the N-bit signal is not finished. As a result, since an erroneous signal is not completed for the receiving, no remote control is malfunctioned.