Saikoku-ji, Buddhist temple in Onomichi, Japan

Saikoku-ji is a Shingon Buddhist temple in Onomichi whose main hall (kondō), built in 1386, and three-story pagoda, donated in 1429, are both Important Cultural Properties. The Niomon Gate, built in 1648, holds a 2-meter straw sandal. The temple is the head temple of the Daigo-ha Shingon sect.

According to temple tradition, Gyōki founded Saikoku-ji during the Tenpyō era (729–749) after a dream of Kamo Myōjin. A fire destroyed most buildings in 1066, but the monk Keiban rebuilt them under Emperor Shirakawa's order, and by 1081 a large complex covered the slope of Atago-yama. In 1108 it became an imperial prayer temple with over 100 branch temples, and in 1312 Emperor Hanazono granted the name Saikoku-ji.

Saikoku-ji is the special temple of the Chūgoku 33 Kannon pilgrimage, sitting between Jōdo-ji and Senkō-ji, and stop 16 on the Chūgoku 49 Yakushi route. It is also stop 19 of the Sanyō Hana no Tera 24 temples and stop 6 of the Bingo 33 Kannon circuit. Its main image, a hidden Yakushi Nyorai, was reportedly brought from Zentsū-ji in Sanuki.

Plan time for climbing the stone stairway, as the elevation gain requires decent physical effort. Interior access involves navigating different levels within the temple grounds.

The 2-metre straw sandal at the Niomon Gate, built in 1648, is the temple's symbol; the gate and the main hall of 1386 and the three-storey pagoda of 1429 are all Important Cultural Properties and part of a Japan Heritage site.