A navigation apparatus includes an unregistered road detecting means for setting up a detection start point and a detection end point for an unregistered road on registered roads which are respectively located before and behind sections in which matching result data indicates a free state, respectively, the matching result data indicating a matching state when the vehicle is traveling each of the registered roads, for performing a coordinate transformation on a traveling path which is created from positioning data and which is extending between the two points so that the traveling path has coordinates which match with the coordinates of a registered road between them, and for detecting the coordinates of the unregistered road from a portion of the coordinate-transformed traveling path which does not overlap any registered road, and a road data generating means for creating road data about the unregistered road from the coordinates of the unregistered road.