Penicillin was discovered by Alexander Fleming (U. K.) in 1928. The method of the mass production of penicillin was established by the special project for stable supply of penicillin in United States in 1943, and it relieved many injury soldiers from an infectious disease in World War II. In Japan, Penicillin Committee was organized at the beginning of 1944 and the research and development of penicillin were started. The committee obtained pure penicillin about nine months after starting the research. Some institutions also tried the development of penicillin uniquely. In Chiba Army Hospital, Mr. Ogawa (pharmacist, second lieutenant) and Dr. Tanigawa (School of Medicine, Chiba University, military physician, first lieutenant) carried out penicillin production. In this lecture, I would like to introduce the research and development of penicillin in Japan and Chiba Army Hospital under World War II.