It is impossible to perform a handover between mobile terminals. Moreover, when performing a session handover between terminals which are mobility-managed by separate Mobile IP HA, it is impossible to normally handle an Uplink packet by the IETF standard technique. Provided is an inter-terminal session handover method using a function (9) for managing bind information between terminals to be arranged on a network as slaves by a user, an address conversion function (5), a function (7) for performing encapsulation between HA, and a function mounted in the terminal for reporting the bind information to the bind information management function (9) and causing a handover trigger.