A travel-estimated road, which a vehicle is estimated to travel, intersects with a cross road at an intersection. A search area shaped of a sector centering on the intersection is defined to have a central angle to include an extending direction of the cross road. An arc intersecting point is then defined where an outer circumference arc of the search area intersects with the cross road. A display position of the road name of the cross road on a road map is determined based on a line segment between the intersection and the arc intersecting point. Thus, the road name of the cross road can be displayed in a position, which is in proximity to the travel-estimated road so as to allow a user to clearly recognize that the displayed road name indicates the cross road irrespective of the configuration of the cross road.