Untō-an, Buddhist temple in Minamiuonuma, Japan.

Untō-an is a Sōtō Zen temple in the Yunodō district of Minamiuonuma, Niigata Prefecture, with the mountain name Kinjō-zan and Shakyamuni Buddha as its principal image. Its grounds are entered through a red gate (akamon) built in the Eikyō era and rebuilt in the Edo period; the main hall was also rebuilt in the Edo period under the carpenter Oguro Jin'na from Izumozaki.

According to temple tradition, the nun Fujiwara no Senpi, mother of Fujiwara no Fusasaki, founded a hermitage here, and in 701 Fusasaki built a convent for her. In 1430 Uesugi Norizane invited Kensō Keiji, a disciple of Kettō Nōshō of Kōun-ji, to re-establish it as a Zen temple, the first Sōtō school temple in Echigo. Norizane retired here in 1447, and the temple grew to hold 27 branch temples.

The temple's name is also written 雲洞院 in the Kamakura Ozōshi. Its approach from the red gate lies over stones inscribed one character each from the Lotus Sutra, giving rise to the saying "Did you tread Untō-an's earth, taste Kankō-ji's miso?"—walking the path was held to bring benefit.

Untō-an is at 660 Kumoito, Minamiuonuma, with parking on site. From Rokkamachi Station on the JR Jōetsu Line it is about 5 km southeast, roughly 12 minutes by car; the Minami-Uonuma sightseeing bus toward Shimizu stops at Kumoito Iriguchi, about 30 minutes on foot from there. From Shiozawa Station it is about 5 km east, 10 minutes by car.

Beneath the approach path from the red gate, stones inscribed with one character each from the Lotus Sutra are buried. An old saying asks whether you have trodden Untō-an's earth or tasted Kankō-ji's miso, and walking the path was held to bring benefit.