The vehicle-installed remote control unit includes a receiver receiving a command signal transmitted from a transmitter dedicated to a vehicle, and a controller controlling a part of the vehicle in accordance with the command signal received by the receiver. The controller has a noise-decision function of deciding whether or not a signal received by the receiver is a noise, a record function of recording noise information including at least information specifying a time at which the signal received by the receiver is decided to be the noise by the noise-decision function in a memory included in the controller, and an output function of outputting the noise information recorded in the memory to an external device in response to a command received from the external device.