Rizō Takeuchi (竹内 理三 Takeuchi Rizō, December 20, 1907–March 2, 1997) is a Japanese historian. He is best known for his work on historical records pertaining to the ancient and Middle Ages of Japanese history.
Upon graduation, he began work at the Historiographical Institute of the Imperial University of Tokyo, where he eventually became the director in 1965.
He taught at the Kyūshū University, the Historiographical Institute of the University of Tokyo, and Waseda University.
Takeuchi's research produced a number of major books including:
- Nihon Jōdai Jiin Keizai-shi no Kenkyū, 1934
- Jiryō Shōen no Kenkyū, 1942
- Ritsuryōsei to Kizoku Seiken
Of particular significance is his complete collection of historical documents spanning three historical Japanese period:
- Encyclopædia Britannica (2007)
- Nihon Rekishi Daijiten (2000-2001)