It is possible to provide a radio sensor system capable of saving power. In a relay controller, a radio wave transmitted for power supply from a relay station to each sensor is stopped at a certain time interval and a command for performing time correction in each sensor is transmitted. When the radio wave transmitted from the relay station to each sensor for power supply is stopped, each sensor executes time correction of an internal clock function. Moreover, in the relay station controller, when an error has occurred in a message containing measuring data which has been transmitted from each sensor, the radio wave for power supply to be transmitted from the relay station to the sensor which has transmitted the message is stopped for a predetermined period of time so as to request retransmission of the message.
