noun
graduate school of science
Refers to the graduate division of a university that encompasses science-related departments, such as physics, chemistry, biology, etc.
彼は東京大学の理学研究科で物理学を専攻している。
He is majoring in physics at the Graduate School of Science of the University of Tokyo.
Compound of 理学 (rigaku, 'science') + 研究科 (kenkyūka, 'graduate school').