To miniaturize a portable communication device and to enhance the degree of design freedom by miniaturizing a battery for the portable communication device in a keyless entry system controlling a door lock mechanism by transmitting and receiving signals between the portable communication device and an in-vehicle communication device.

The portable communication device transmits a response signal in response to the reception of call signals continuously transmitted from the in-vehicle communication device. When the in-vehicle communication device receives the response signal, the position of the portable communication device is estimated according to the received result, and a door lock device of a vehicle is controlled according to the estimated result. The in-vehicle communication device estimates the position of the portable communication device using interior antennas 231, 232 and 233 provided inside the vehicle, and transmits charging radio wave through the interior antennas 231, 232 and 233 according to the estimated result. The battery of the portable communication device is charged when the portable communication device receives the charging radio wave.