A vehicle body communication device (200) transmits a request signal to both a wheel side sensor (31) that is provided in a valve (24) of a wheel (22), and a tire side sensor (32) that is embedded in a tire tread (28). When the wheel side sensor (31) and the tire side sensor (32) receive the request signal from the vehicle body communication device (200), respective return signals are transmitted to the vehicle body communication device (200). The respective transmission patterns are set to be different.