Route search is performed considering the fact that traffic conditions differ according to lane even for the same road. A navigation device performs route search, using link costs (link travel times) classified by lane. For example, the navigation device searches for a route having the lowest total cost to the destination, using link data that determine cost for each lane of a component link of a road on a map. A cost of a lane on which a vehicle runs to move to a next link, being the cost of any lane of the link, is used as a cost of a link on a route.