In a navigation system, an index information (idx(di(S))) tagged to an objective differential information (di(S)) which is a part of the entire differential information (di) is transmitted from a navigation apparatus (200) to a navigation server (100). Specifically, the index information (idx(di(S))) tagged to the objective differential information (di(S)) pertained to an area (S) containing therein a navigation route (r) for guiding an automobile (2) to a destination position (p2) is transmitted from the navigation device (200) to the navigation server (100). Further, the navigation server (100) determines whether the objective differential information (di(S)) is temporally valid or not, and the objective differential information (di(S)) is added to a navigation map information on condition that the determination result is affirmative. Furthermore, a new navigation route (r) can be set and output according to the updated navigation map information to which the objective differential information (di(S)) has been added.