Kazuhiko Nishijima (born 4.10.1926) is a Japanese theoretical physicist. He graduated from the University of Tokyo (1948). In 1954 he received the degree of Doctor of Philosophy at the University of Osaka. He worked there (1950-59). In 1959-67 he was professor at the University of Illinois (USA), and from 1967 at the University of Tokyo.
His research was in elementary particle physics and quantum field theory. In 1954, independently of M. Gell-Mann, he introduced the concept of strangeness (a new quantum number) and discovered the law of conservation of strangeness. For strange particles he derived a formula connecting the electric and baryon charges, the strangeness and the third projection of the isotopic spin (the Gell-Mann–Nishijima formula). He developed a scheme for classifying elementary particles. In 1957 he predicted (independently of others) the electron and muon neutrinos.
Foreign member of the USSR Academy of Sciences (1982).