Kaigan-ji, Buddhist sanctuary in Tadotsu, Japan.

Kaigan-ji is a Shingon Daigo-ha temple in Nishishirakata, Tadotsu, Kagawa Prefecture, made up of two parts: the main precinct (honbō) with its main hall, and the Oku-no-in hall about 400 m away, which houses a statue of the infant Kūkai. The two are separated by the Sanuki Hama Kaidō road and the JR Yosan Line, and a youth hostel is attached.

According to temple tradition, Kūkai was born in 774 at the Okunoin, and in 807 he founded the main hall, enshrining a Shō Kannon or Miroku statue. In 816 he carved his own image and built the Daishidō. In 1583 the buildings burned during Chōsokabe Motochika's advance and were rebuilt from 1590. In 1816 a dispute with Zentsū-ji over Kūkai's birthplace was settled by the shogunate: Zentsū-ji is the birthplace, Kaigan-ji the sacred site of his first emergence.

Kaigan-ji's name is written with the characters for sea and shore, and its pilgrimage verse mentions boats passing offshore and the inkstone-like waves. The main hall holds a set of Twenty-Five Bodhisattvas in the Clouds painted along the upper walls, and the temple's two precincts each keep their own stamp office for pilgrims of the Bekkaku 20 and the Shikoku 36 Fudō circuits.

Kaigan-ji has two parts: the main hall (honbō) and the Okunoin hall about 400 m away, separated by the Sanuki-Hama road and the JR Yosan line. Kaigan-ji Station on the Yosan line is 0.4 km from the temple. The Okunoin's Fudō hall can be reached by car up to the hall itself.

The main hall (hondō) was rebuilt in 1856, and the temple's two parts are split by the Sanuki Hama Kaidō road and the JR Yosan Line. The temple also runs a youth hostel. Its mountain name, Kyōnō-zan, comes from a legend that the young Kūkai copied the Lotus Sutra one character per stone and deposited the stones here.