Abstract: Japan’s National Ocean Strategy has gone through an expanding shrinking re expanding development phase. In view of the resources, environment, strategic and economic value in Arctic area, Japanese government has positively participated in Arctic affairs and pursued the Arctic benefits under the frame of national ocean strategy. The strong intervention towards Arctic affairs made by Japanese government may cause a significant change in Arctic Geopolitical Structure. This paper analyzes the development process and the future trend of the Japanese national ocean strategy, and draws a conclusion that the Japanese national ocean strategy is mainly influenced by the nation identification of Japan (to be a marine nation or continental nation), the geopolitical pattern of East Asia, and the marine super power US. This paper also reflects that the Japanese national ocean strategy will show a tendency of expansion in the future. Then, this paper analyzes how Arctic geopolitical structure will influence Japan's national ocean strategy and the trend of the changes of Japan’s national ocean strategy in the future, puts forward that Japan will restrict China in developing Arctic engagement strategy, having better diplomatic relations with Russia and enhancing its military force. Finally, studying the change of the Arctic Geopolitical Structure should be based on the standing points of China, US, Russia, Japan.

Key words: Arctic, geopolitical structure, Japan’s national ocean strategy