Koken Nosaka (?? ??, Nosaka Koken, 17 September 1924 – 18 April 2004) was a Japanese politician.
He was first elected to the Diet of Japan in 1972, representing a district in southern Tottori Prefecture.
A member of the Social Democratic Party, he served as construction minister and chief cabinet secretary under Prime Minister Tomiichi Murayama.Liberal Democratic Party politician Yohei Kono described Nosaka as "the main player" in forming the LDP-SDP coalition governments of the mid-1990s.