In our contemporary society, globalization and multiculturalism lead to create new forms of political community beyond the nation-states with homogenous identity. The European Union(EU) is the best known example of this transnational political community. Habermas understands the political integration of European society as a significant milestone for the shift “from classical international law to cosmopolitan order.”This paper examines Habermas’s understandings of European integration and the European Constitution from his cosmopolitan perspectives. Habermas begins his discussion about Europen political integration with his careful analysis of challenges that European nation-states are facing internally and externally in the globalized and transnational era. To overcome those challenges, Habermas requests that European integration should move forward from economic(monetary) union to political union. He points out that the European constitution is essential for this normative goal. The notion of ‘constitutional patriotism,’ which means a commitment or loyalty to common European political culture, provides a theoretical foundation in this constitutional framework. He further argues that European identity is rooted in the particular historical experience and its ‘reflexive’ nature, and that European civic solidarity and European public sphere evolve through the ‘learning process.’ Furthermore, he suggests that the ‘Core Europe’ such as Germany and France should take a leading role in the process of European integration. Then this paper provides several problems and future tasks in Habermas’s discussion on European political integration and the European constitution, and suggests the possibilities of Northeast Asian political integration as ‘another’ version of postnational political community.