A navigation system has a current position detecting unit 32 for detecting a current position, a map data acquiring unit 31 for acquiring map data including road data representing an HOV lane and an ordinary lane in a single link; a driving link decision unit 38 for identifying a link of driving from the current position information indicating the current position detected by the current position detecting unit 32 and from the road data included in the map data acquired by the map data acquiring unit 31, and for outputting as a driving link; and a driving lane decision unit 39 for making a decision as to whether the driving lane is the HOV lane or ordinary lane from the driving link identified by the driving link decision unit 38.