The Japanese society has seen a powerful movement of constitution amendment since the 21^st century. Although this movement temporarily ended with Japanese government's reinterpreting the Article 9 of the Japanese Constitution, the problems involved have not been settled yet. The reason is that the Japanese Constitution has a worldwide significance since its initial creation was beyond the framework of a nation-state. Therefore, its problems can only be solved in a new cosmopolitan system. Accordingly, its historical process and contemporary significance need to be reinterpreted from the perspective of a new cosmopolitanism, and such a reinterpretation will benefit the theoretical construction of a new cosmopolitanism in turn.