VEHICLE-MOUNTED DEVICE

A vehicle-mounted device 100 is arranged to be capable of attaching and detaching a portable device 10 including a display unit 11. Also, the vehicle-mounted device 100 includes a display unit 131 and a controller 140, and the controller 140 detects that the portable device 10 is attached or the portable device 10 is detached, and turns off the display unit 131 when it is detected that the portable device is attached. Thereby, the power consumption of the vehicle-mounted device 100 can be reduced. Also, the same information is not displayed on the display unit 131 and the display unit 11, and it is unnecessary to execute a process that mutually synchronizes the display timing of information displayed on both display units.