An excretion detection device 100 comprises a radio transmission unit 180 that is configured to transmit radio signals to a transmitter-receiver 20, the radio signals containing temperature information detected by a temperature sensor 130 and a diaper identifier which is unique to a disposable diaper. The transmitter-receiver 20 comprises: a diaper identifier authentication unit 23 configured to authenticate the diaper identifier which is contained in the radio signals received from the excretion detection device 100 when a field intensity of the received radio signals is higher than a predetermined threshold and a reception processing unit 25 configured to execute processing of the diaper identifier authenticated by the identifier authentication unit and the temperature information that is associated with the authenticated diaper identifier.
