Masao Kotani (小谷 正雄, Kotani Masao, January 14, 1906 – June 6, 1993) was a Japanese theoretical physicist, known for molecular physics and biophysics. Kotani was born in Kyoto and spent his primary and middle school days in Osaka. He moved to Tokyo to enter the First Higher School and then the Imperial University of Tokyo. In 1929, he received his BSc degree in physics and was appointed as a lecturer at the faculty of engineering in the Imperial University of Tokyo. Three years later, he became an associate professor in the physics department. In 1943, he received the degree of DSc and was promoted to a full professor. In 1965, he moved to Osaka University as a professor in the faculty of engineering science. He retired from the chair in 1969. One year later, he was elected president of the