A communication
navigation system, wherein a navigation apparatus requests a recommended
route guidance data to a
information center and guides a user of the navigation apparatus to a destination by using the recommended
route guidance data received from the
information center.In this present invention, the navigation apparatus transmits version data of road data held in the navigation apparatus at the request to the
information center. The information center prepares a guidance data of recommended
route using latest road data held in the information center, and transmits the data to the navigation apparatus. When the information center transmits the guidance data, the information center selects the type of data of the road links along the recommended route, in the guidance data, by comparing the version data received from the navigation apparatus and the version data of each road link along the recommended route. If each data of road links along the recommended route is considered to be contained in the road data held in the navigation apparatus, the information center transmits the only data which enable to specify the road link from the road data held in the navigation apparatus. On the hand, if each data of road links is considered not to be contained in the road data held in the navigation apparatus, the information center transmits whole data of the road link. Therefore, the navigation apparatus can generate the route guidance data by extracting road
link data, from its own road data, corresponding to the road link specified by transmitted data and by reconstructing road
link data using transmitted data.