A request signal transmitted from LF antennas of a vehicle-mounted unit is received by a radio terminal through an LF antenna. In response to the request signal, the radio terminal transmits a response signal from an antenna. The response signal is received by an RF unit of the vehicle-mounted unit. The vehicular remote control device controls an operating state of a vehicle-mounted device depending on the judgment of a match between the response signal and identification information inherent in the vehicle. The radio terminal has a light-emitting diode. When the radio terminal receives a failure diagnosis signal that is transmitted instead of the request signal, the radio terminal does not transmit a response signal, but energizes the light-emitting diode.