Seiganto-ji (青岸渡寺), Temple of Crossing the Blue Shore, is a Tendai Buddhist temple in Wakayama Prefecture, Japan. In 2004, it was listed as a UNESCO World Heritage Site along with other locations, under the name "Sacred Sites and Pilgrimage Routes in the Kii Mountain Range". According to a legend, it was founded by the priest Ragyō Shōnin, a monk from India. The temple was purposely built near Nachi Falls, where it may have previously been a site of nature worship. Seiganto-ji is part of the Kumano Sanzan shrine complex, and as such can be considered one of the few jingū-ji (shrine temples, see article Shinbutsu shūgō) still in existence after the forcible separation of Shinto and Buddhism operated by the Japanese government during the Meiji restoration.
It is Saigoku Kannon Pilgrimage's No.1 (first stop) and an Important Cultural Properties of Japan.