A navigation system includes: an information center; a navigation device of a vehicle communicating with the information center; a communication unit transmitting information of a destination to the information center; a center side transmission unit searching positional information of the destination in a database of the information center and transmitting the positional information to the navigation device; a calculation unit of the navigation device calculating a first route to the destination; a navigation side transmission unit transmitting first route calculation result to the information center; and a determination unit of the information center calculating a second route to the destination, comparing second route calculation result with the first route calculation result, and determining whether the navigation device guides a route to the destination based on the first or second route calculation result.