In the ubiquitous network, it is important to provide not only the continuous connectivity but also the strong security.
The IPsec-VPN technology archives some kind of the ubiquitous network with providing one virtual IP address and the encrypted communication channel.
However, if the user's terminal moves between networks, its IP address will be changed by roaming process, and the IPsec-VPN connection must be disconnected until IPsec-SA is shared with new IP address.
In this paper, we propose the new method to solve this problem.