Disclosed is a technique that, in a network-based local mobility management method, reduces the load of a network node for managing position information of a mobile terminal and achieves a high scalability with respect to the number of mobile terminals. According to the technique, a LMA (Local Mobility Anchor) (1000) assigns a primary network prefix to each of MAGs (Mobility Access Gateways) (1010, 1020) under the control of the LMA and registers, in a routing table, the correspondence relationship between the position information of each of the MAGs and the primary network prefix assigned to each of the MAGs. In addition, among MNs (MobileNodes) (1030, 1040) connected under the MAGs, for a MN that uses an address including a secondary network prefix, the LMA registers, in a binding cache, the correspondence relationship between the MN and the position information of an MAG to which the MN is connected.