Multimedia service in wireless IP networks, most delays and disruptions happening on the handoff of nodes are related to AAA. There were many studies on attempting to reduce the delay happening on the handoffs, and among them, there is the shadow registration as a suitable method for seamless mobility. Shadow registration is a method preparing against the following handoff by registering to all neighboring cells in prior, and is efficient in reducing the handoff delay. However, this method causes heavy traffic as well as the waste of resources. In order to prohibit the increase of traffic among the nodes while having the reducing effect on delay time, we proposes a technique and algorithm for composing Region-based Shadow Registration (RSR) that provides seamless mobility, which does not cause traffic and the waste of resources. We have introduced a cell division scheme for minimal Shadow Registration and its algorithm. The results of the experiments performed by simulations displayed the identical effect of reducing the delay as shadow registration while significantly reducing the traffic among the nodes.