Tettsugikai (February 18, 1219 - October 18, 1309) was a Buddhist monk of Soto Sect in the mid-Kamakura period. He hailed from Echizen Province.
After receiving Buddhist precepts at Mt. Hiei, he became a disciple of Dogen, a monk of Kosho-ji Temple at Fukakusa in Yamashiro Province, and practiced Zen meditation under him. Since then, he followed Dogen and held important posts, including Tenzo (one of six administrative posts at a Zen temple), at Eihei-ji Temple. After Dogen died, he streamlined the regulations and rituals of Eihei-ji Temple under Ejo. He was thereafter inaugurated as the third chief priest of Eihei-ji Temple, but after the death of Ejo, he moved to Kaga Province and became the founder of Daijo-ji Temple by converting it from a Shingon Sect temple to a Zen temple. Keizanjokei, who laid the foundation of the development of Soto Sect, was his disciple.