To allow a slave station in a standby state to interrupt a current communication when the slave station detects a fault in the radio supervisory system consisting of a plurality of slave stations and a base station.

When a sensor section 7 senses a fault while a slave station is in standby, the mode of the slave station is changed from the standby state to receive a signal addressed to itself from a base station into a transmission state (2nd changeover device 20), the slave station uses a 2nd spread code to send sensor section sending data and slave station identification data or the like to the base station. The base station is provided with a 1st demodulation section 38 using the 1st spread code to demodulate a camera video signal and with a 2nd demodulation section 39 to use a 2nd spread code. Thus, in the case of receiving the spread spectrum signal using the 2nd spread code, the 2nd demodulation section 39 demodulates the data. Based on the slave station identification data included in the demodulation data, the caller slave station is identified and the base station allows the slave station to send the camera video signal using the 1st spread code.