PURPOSE: To prevent production of sensitivity suppression by extracting and storing message data from a signal received by a storage means prior to operation of a system control circuit and then operating the system control circuit.

CONSTITUTION: An ID collation section 3A of a decoder 3 extracts a received ID code from a signal received and detected by a reception section 2 based on a synchronizing signal from a synchronization detection section 3B and provides a matching signal to a data buffer 7 and a timer 8 when the received ID code is matched with an ID code stored in a memory 4. Then the timer 8 starts time-counting and the data buffer 7 extracts and stores message data from the signal received and detected by the reception section 2. Furthermore, the timer 8 inputs a start signal to a CPU 5 in the same timing as the end of storage of the message data, the CPU 5 starts the operation and extracts the message data stored in the data buffer 7 and processes the data and displays the result onto a display device 6.