Sekinari Nii (二井 関成, Nii Sekinari, born March 20, 1943) is the former governor of Yamaguchi Prefecture in Japan.

Sekinari Nii was born in Mine, Yamaguchi. He studied in University of Tokyo. After graduation in 1966, he started work in the Ministry of Home Affairs. He was elected as governor of Yamaguchi Prefecture in 1996.

• 政治家情報 〜二井 関成〜. www.senkyo.janjan.jp ザ･選挙 (in Japanese). JANJAN. Archived from the original on 2007-12-30. Retrieved 2007-12-08.

• Official website