A stopping vehicle estimating unit estimates one of a number of stopping vehicles and a length of a stopping vehicle line of different vehicles that are stopping at a traffic light along an estimated driving route ahead of the own vehicle closer to the traffic light than the own vehicle, based on a position information of a site at which a traffic light is provided, an own vehicle position, an own vehicle speed, and traffic information. A passable time zone estimating unit estimates a passable time zone during which the own vehicle is able to pass by the traffic light, based on the one of the number of stopping vehicles and the length of the stopping vehicle line that have been estimated by the stopping vehicle estimating unit, and on schedule information.