In Japan, public opinion survey has been considered to be introduced from the United States as a tool indispensable to democracy. Such a view has been inherited in academic circles as well as in actual society for a long time that public opinion surveys are conducted in order to make the voice of the people as political subjects reflect in politics. And historical studies on public opinion survey have tended to take up development of survey methodology mainly. Some public opinion surveys, however, do not remain in that category. The purpose of this paper is, taking up public opinion surveys by foreign governments, to make clear the political nature which the social technology of public opinion surveys originally has. USIA (United States Information Agency) made public opinion surveys in Japan in the 1950s. Since these surveys have been strictly confidential for a long time, there is almost no opportunity for ordinary people to know them. Then, this paper attempts to describe the purpose or process of the public opinion surveys which USIA conducted in Japan those days. After it was established by the Eisenhower Administration in August, 1953, USIA strengthened investigation section and began to conduct various public opinion surveys in spite of State Department's criticism. USIA assigned research officers under PAO (Public Affairs Officer). The research officer has been assigned in Japan in October, 1955. USIA conducted various surveys, for example, "Public Opinion Barometer" surveys, under the research officer's directions in Japan. USIA thought that a cold war was a war which acquired "man's heart" and persuaded foreign people. It conducted "Barometer" surveys which measured opinions, image of America, and attitudes of foreign peoples in order to persuade them. Therefore, the public opinion surveys have constituted USIA's strategy of "Public Diplomacy", or propaganda activities, to foreign countries.