The route control method and the route setting device according to the present invention is configured such that a learning unit is prepared for each path, a function form of the learning unit of the path in forwarding a packet is adjusted by having traffic information (packet arrival rate, queue length, and the like) and congestion information (congested or not congested) of this path as teacher data, and when this path is congested, changing to a path with an output of no congestion among the learning units is executed. Thus, since the learning unit optimizes the function form, changing to an alternative path can be immediately executed even when the congestion incidentally occurs on the path.