Tenryū-Okumikawa Quasi-National Park is a quasi-national park in the Tokai region of Honshū in Japan. It is rated a protected landscape (category V) according to the IUCN. The park includes the gorges of the upper Tenryū River, Sakuma Dam and its surrounding forests, Atera Seven Falls, Chausu Mountains and Mount Horaiji. It straddles the border between Shizuoka, Aichi and Nagano Prefectures. The area was designated a quasi-national park on October 1, 1969.