Nakain Michinari (1222 - 8 January 1287; 中院 通成) was Minister of the Interior of Japan in the apex of his career.
Nakain Michinari was born into the Nakain clan, a branch of the Minamoto clan, as the son of Nakain Michikata, who was the son of Minamoto Michichika. He thus may be called Minamoto Michinari in old texts. His grandson was Nakain Michishige.
His tenure as Minister of the Interior lasted part of 1269; in that title, he was preceded by Kazanin Michimasa and succeeded by Nijō Morotada.