The aim of this article is to reconsider the meaning of the Treaty of Peace and Amity between Japan and the United States of America signed at Yokohama on March 31, 1854 and to place it in the context of world history and Japanese history. When proceeding with the analysis, I considered three issues: (1) war and diplomacy two expressions of international politics, which are still as important today as in the 1850s given current international politics; (2) a comparison of Japan-U.S. diplomatic power, which is the key when negotiations take place between states; and (3) the avoidance of outdated views of history, which is important to understanding modern history. Since Commodore Perry's expedition to Japan and the Japanese encounter with the West was a big event in our history, many documents and materials are reserved in both countries including pictures and prints. Although it is necessary to analyze this chain of events-the cause, the process and the results of the first official U.S.-Japan political negotiation-by a pluralistic approach, this article exclusively analyzes two factors: one is the purpose of Commodore Perry's expedition to Japan (cause) and the other is the negotiation between Japan and the U.S. (process), that enabled both sides to avoid war through the talks of Uraga in 1853 and of Yokohama in 1854. The Treaty of Peace and Amity (result), which eventually led to the opening of Japan, can be highly evaluated because it was a negotiated treaty that was not accompanied by war. Modern Japan was founded on "the modern international regime of four pieces of polity" (the Great Powers, the colony, the loss treaty nation and the negotiation treaty nation), which later changed its feature in 1895, 1905 and 1945.