a memory that stores traffic information; and

a controller that:

creates prediction traffic information based on the traffic information stored in the memory, the prediction traffic information including restriction information and congestion prediction information;

searches a route to a destination, the route including at least one link;

calculates a predicted passage time of each link in the route;

obtains, for each link, the prediction traffic information at the predicted passage time from the created prediction traffic information;

determines whether the obtained prediction traffic information for all links of the route can be distributed; and

extracts the restriction information for each link of the obtained prediction traffic information as distribution information according to a predetermined priority when the obtained prediction traffic information for all links of the route cannot be distributed.