A vehicle-mounted device including an input unit connected to a device compatible with a predetermined interface standard and inputting a digital content from the device and an output unit connected to a device compatible with the predetermined interface standard and outputting a digital content to the device, the vehicle-mounted device comprising: first authentication means for performing first authentication processing in which, when a first device compatible with the predetermined interface standard is connected to the output unit, the vehicle-mounted device and the first device authenticate the vehicle-mounted device as a source device at a transmission side of the digital content and authenticate the first device as a sink device at a reception side of the digital content; second authentication means for performing second authentication processing in which, when a second device compatible with the predetermined interface standard is connected to the input unit while the digital content is output to the first device authenticated as the sink device from the output unit, the vehicle-mounted device and the second device authenticate the vehicle-mounted device as the sink device and authenticate the second device as the source device; third authentication means for performing third authentication processing in which the vehicle-mounted device, the second device, and the first device authenticate the vehicle-mounted device as a repeater device for relaying a digital content between the second device authenticated as the source device and the first device authenticated as the sink device; determination means for determining whether a condition for providing the digital content from the second device authenticated as the source device to the first device authenticated as the sink device is satisfied or not; and content output control means configured such that, when the determination means determines that the condition for providing the digital content from the second device to the first device is satisfied, the digital content from the second device which is input from the input unit is relayed and output to the first device via the output unit after the third authentication means finishes the third authentication processing. first authentication means for performing first authentication processing in which, when a first device compatible with the predetermined interface standard is connected to the output unit, the vehicle-mounted device and the first device authenticate the vehicle-mounted device as a source device at a transmission side of the digital content and authenticate the first device as a sink device at a reception side of the digital content; second authentication means for performing second authentication processing in which, when a second device compatible with the predetermined interface standard is connected to the input unit while the digital content is output to the first device authenticated as the sink device from the output unit, the vehicle-mounted device and the second device authenticate the vehicle-mounted device as the sink device and authenticate the second device as the source device; third authentication means for performing third authentication processing in which the vehicle-mounted device, the second device, and the first device authenticate the vehicle-mounted device as a repeater device for relaying a digital content between the second device authenticated as the source device and the first device authenticated as the sink device; determination means for determining whether a condition for providing the digital content from the second device authenticated as the source device to the first device authenticated as the sink device is satisfied or not; and content output control means configured such that, when the determination means determines that the condition for providing the digital content from the second device to the first device is satisfied, the digital content from the second device which is input from the input unit is relayed and output to the first device via the output unit after the third authentication means finishes the third authentication processing.