When a vehicle moves into a radar prohibited area preset for the neighborhood of a facility that suffers adverse effects from radar waves, emission of radar waves is stopped, and a voice guidance such as “Radar monitoring is stopped” is sent to a speaker via a voice output unit. Moreover, during a period in which a vehicle is located in a radar prohibited area, an icon that indicates that a radar is being stopped, a mark that indicates an institution for which the radar prohibited area is set, and the scope of the radar prohibited area are displayed on a map image.