Japan regarded the World War I as 〞god's bless in Taisyo〞. They took the excuse that allied with England to declare war with Germany within the minimum goal of seizing German's base in the Far East, to realize the supreme goal-achieve the dominant position in China. Japan tried hard to push the idealism diplomacy in Paris Peace Conference after the war in order to build the new order surrounded with Japan in East Asia. After the war, the United States and England returned to East Asia, Japan had to make a strategic contraction because of the great disparity in comparison with the United States and England. Meanwhile, Japan intended to transform their diplomatic strategy in the Washington Conference, but failed. From then, Japan's diplomatic strategy became clearer than before, and the Washington Conference had become the start point of their 〞Shidehara Diplomacy〞.