Keiko Nagaoka (永岡 桂子, Nagaoka Keiko?, born December 8, 1953) is a Japanese politician serving in the House of Representatives in the Diet (national legislature) as a member of the Liberal Democratic Party. A native of Tokyo and graduate of Gakushuin University she was elected for the first time in 2005. Her husband was politician Yoji Nagaoka, who committed suicide on August 1, 2005.