The purpose of this paper was to make clear the trend of science education refotm in postwar Japan. In those days, Fumiyoshi Oshima (1894-1986) Who worked at the textbook bureau in the Ministry of Education played an important role in the compilation of textbook and the preparation of courses of study. So through the study of documents and records in F.Oshima's possenssion, the following results were reached: (1) The Ministry of Education reformed science education in the democratic ways. (2) According to the researches on the actual condition, the Ministry of Education tried to make the best use of them in order to design the objects and contents for the new science education. (3) In early postwar Japan, the circumstances surrounding schools had a good grounding in spreading the new science education.