Riken (理研?) is a large research institute in Japan. Founded in 1917, it now has about 3,000 scientists on seven campuses across Japan, the main one in Wakō, just outside Tokyo. Riken is a Designated National Research and Development Institute (formerly an Independent Administrative Institution) whose formal name in Japanese is Rikagaku Kenkyūsho (理化学研究所?), and its full name in Japanese is Kokuritsu Kenkyū Kaihatsu Hōjin Rikagaku Kenkyūsho (国立研究開発法人理化学研究所?).
Riken conducts research in many areas of science, including physics, chemistry, biology, medical science, engineering, high-performance computing and computational science, and ranging from basic research to practical applications. It is almost entirely funded by the Japanese government, and its annual budget is about ¥88 billion (US$760 million).