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