When handover is performed from a first network to a second network, a home agent transmits a reply request message to a terminal through the first network after new configuration of a tunnel for transmitting and receiving a packet through the second network. If the home agent receives a reply message corresponding to the reply request message through the first network, the home agent detects that the configuration of the tunnel for transmitting and receiving the packet through the first network can be deleted, and deletes the configuration of the tunnel.