An example navigation system enables searching for an optimum route through a one-time route searching process where several destination or departure locations exist. The navigation system includes a point of interest (POI) attribute information database for accumulating POI attribute information, a network data edit unit and a virtual node setup unit. The navigation system determines whether there is a plurality of POIs in a certain departure location and/or a destination location by making reference to relevant data in the POI attribute information database. If there are several POIs, the virtual node setup unit sets up a virtual node connected to each node of the plurality of POIs through links having identical link cost. The network data edit unit then adds the virtual node to the searching network data, and a route search unit functions to search for routes using the searching network data containing the added virtual node.