In the discipline of International Relations, it is usually said that idealist was dominant during the inter-war period and realism came to be dominant after the Second World War. But this article points out that those who are classified as idealists were also base on the sense of dominant power of Great Britain and the United States. This is intended to explore the implications of the change of international thoughts from the inter-war period to the post-Second World War era by paying special attention to the discourses on state sovereignty.