The invention provides a route updating method which reduces the flow rate of updating notifications, which are circulated in a network, to improve the scalability. A micromobility network includes routers connected in a tree connection and radio base stations connected to the routers in the lowest layer such that an updating notification of a route from a mobile terminal is repeated in order from a radio base station to successive higher order routers to update the route and a packet is distributed along the updated route. In the mobility network, directly lower order routers to each router are numbered to the numbers 1 to n with reference to the direct lower order router accommodation number n, and a route from the radio base station to the router in the highest layer represented by a route number composed of the numbers of the thus numbered routers is applied to the radio base station. Upon updating notification, the route number is referred to to determine a stage number m of a transmission range and the updating notification is transmitted to a higher order router corresponding to the stage number m.