A map matching method and apparatus for a navigation system estimates a location of the navigation system on a correct road segment when a GPS signal is invalid. The map matching method creates a database of pairs of locations at which the navigation system encountered GPS signal loss and recovery in the first time. The navigation system conducts a map matching processing when the GPS signal is lost in the second time at the recorded location by incorporating various additional factors to match the current position with a correct road segment. The various additional factors, in addition to the measured data by a dead reckoning process, include road class, road accessibility, road angle, proximity to candidate road, etc.