Ōya-ji (大谷寺) is a Buddhist temple of the Tendai sect in the city of Utsunomiya, Tochigi Prefecture, Japan. According to legend, the temple was established by Kūkai, the founder of the Shingon sect, in the year 810, but this has not been firmly established. The temple was rebuilt during the years 1615 to 1624. The temple is built into the surrounding tuff rock and features a carved figure of the Bodhisattva Kannon with a thousand arms with a surrounding altar.