Naishi Suo was a Japanese waka poet of the late-Heian period. A Court lady in the reign of Emperor s Goreizei, Gosanjo, Shirakawa and Horikawa. Her odes are contained in Shinkokin-wakashu and other anthologies compiled at Imperial orders.
Naishi Suo was born in 1080. She was the daughter of Munenaka Taira, governor of Suo. Her given name was Nakako.
Her oldest poems were composed about the time of the enthronement of Emperor Gosanjo (1069) and her latest around 1094. One of her works is contained in Hyakunin-Isshu (One Hundred Poems By One Hundred Poets).