A vehicle-mounted device includes a first authentication unit for performing first authentication processing in which, when a first device is connected to an output unit, the vehicle-mounted device is authenticated as a source device and the first device is authenticated as a sink device; a second authentication unit for performing second authentication processing in which, when a second device is connected to the input unit while a digital content is being output to the first device from the output unit, the vehicle-mounted device is authenticated as the sink device and the second device is authenticated as the source device; a determination unit; and a third authentication unit for performing third authentication processing in which the vehicle-mounted device is authenticated as a repeater device when a condition for providing the digital content from the second device to the first device is determined to be satisfied by the determination unit.