- Birth: 1527
- Death: After 1610
- Titles: Izumi no kami
- Other Names: Nobusada, Matasuke
- Japanese: 太田 牛一 (Oota Gyuuichi)
Ôta Gyûichi was a writer who kept records of the battles and military affiars of Oda Nobunaga and Toyotomi Hideyoshi, and was the author of the Shinchôkôki. He was born in Kasugai district of Owari province, and first lived at the Jôkan temple there. He later became a Bugyô for Oda Nobunaga in Ômi province.