To solve such a problem that preferentially selecting a road whose traffic situation is not clear or difficult to travel for a driver as a result of route computing to avoid the congestion generated at the road provided with traffic information such as VICS information and the like.

When the link of a target process is a VICS link (S110: YES), the content of the congestion information corresponding to this link is determined (S120). When the degree of the congestion of the link is either smooth or congested (S120: smooth/congested), the cost of the link is reduced by the predetermined amount from the initial value (S130). Meanwhile, when the link is not VICS link (S110: NO) or the degree of the congestion is congested (S120: congested), the cost reduction of the link is not carried out. After carrying out the cost adjustment for each link to be target process of the route computing in order, the optimum route where the total cost to the destination is the lowest is computed (S150).