Recently, to further improve road traffic safety, there have been developed and proposed a variety of technologies for automated driving of a vehicle such as an automobile without manual operation of a driver. In general, during automated driving, an own vehicle automatically travels on a road in accordance with a travel route to a previously-set destination while detecting a position of the own vehicle on a road map. At that time, the travel route and the own vehicle position are displayed in real time on a monitor screen of a mounted navigation system.