With ubiquitous computing, the interconnection of Mobile Ad Hoc Networks (MANET) to Internet is becoming current topic. There are advantages that MANET could organize an independent network without infra-structures. Accordingly to increase of interests about this MANET, Internet Gateway which provides MANET with the internet services is entering the stage as a new challengeable area. Nodes in the overlapped area owned by different Internet Gateway should solve a problem of the selection which Internet Gateway is used to support the internet services. Some solutions related to this selection problem considering environment of the MANET are not satisfactory. An existing alternative based on only the hop counts to choose its gateway have the drawbacks of an exponential decrease of the throughput, because of the node mobility. In this paper we proposed new scheme considering the specific character of node mobility. This proposed scheme could increase throughput of the whole network.