Founded in 663 under Emperor Tenchi by the monk Gyōben, the original name was Ryūgai-ji.

The principal Nyoirin Kannon is Japan's largest clay statue (height 458.2 cm), an Important Cultural Property from the Nara period and one of Japan's Three Great Clay Buddhas.

The Niōmon gate, an Important Cultural Property, was built in 1612 and features A-un lions, a dragon, and a tiger on its four upper corners.

Legend says Gyōben sealed an evil dragon in 'Ryūgai-ike' with a large capstone; touching the keystone is said to cause rain and inspired Okadera's yaku-yoke faith.