The present invention has an object to improve usability of a vehicle-mounted electronic device. The vehicle-mounted electronic device is configured to execute, when unauthorized content is detected by an unauthorized content detecting unit, an audio reproduction restriction on a display device, and when a volume change operation is executed during the audio reproduction restriction, to cause the display device to display a message indicating that the volume change operation has been executed during the audio reproduction restriction. More specifically, the displayed message indicates that the audio reproduction restriction associated with the unauthorized content reproduction is executed and the volume change operation is also executed during the execution. Therefore, the volume can be changed when next content is reproduced, resulting in preventing unexpected high-volume audio from being outputted and thus improving usability.