Remote-controlled in-vehicle device

In a keyless entry system for a vehicle, an in-vehicle device controls door-lock or door-unlock according to a remote-controlling wireless signal from a transmitter. The in-vehicle device determines whether a demodulated signal compliant with a communications rule is obtained from the received wireless signal, and then whether authentication data included in the received wireless signal accords with that stored in the vehicle. The in-vehicle device stores a result of the determination as an analysis result of received electric waves. When a read-out request is received from a diagnosis tool, the stored analysis result is thereby outputted to the diagnosis tool. Based on the outputted analysis result, it is determined whether a cause of non-operation abnormality is a transmitting function of the transmitter or a receiving function of the in-vehicle device.