In this paper I want to approach the theme of “globalization and Japan” from the standpoint of constitutional studies. Constitutions and constitutionalism are important means of reining in political power, and in the modern sovereign state system, constitutions and constitutionalism have been conceived on the level of single states. However, as many scholars have observed, one can see the global spread of power in, for example, the worldwide deployment of the US military using overseas bases throughout the world, and the worldwide activities of transnational corporations based in the US, Europe, and Japan. In sum, this is the global spread of military and social power. It is urgent that we rein in this global power. Although controlling power through single-state-level constitutions and constitutionalism is perhaps still the most important priority, we must also consider the possibilities of global constitutionalism or regional constitutionalism now when power is spreading globally. This paper will explore global constitutionalism, which is now the subject of vigorous discussion for those concerned with global governance. Finally, the paper will link global constitutionalism with the pacifism in Japan's constitution.