Koyasu Shrine, Shinto shrine in Mie Prefecture, Japan

Koyasu Shrine is a small Shinto shrine within the grounds of Ise Jingu's Naiku, at the foot of Mount Kamiji in Ujitachi-cho, Ise. It shares its precinct with Oyama Tsumi Shrine and is enclosed by a tamagaki fence. A wooden torii gate stands at the entrance, and a flower-shaped stone water basin sits before the shrine building.

The shrine's founding date is unknown; its absence from the Engishiki and Enryaku ritual registers suggests it did not exist in antiquity. In June 1872 the Ministry of Education removed unlisted shrines from Naiku jurisdiction, separating it from Ōyamazumi Shrine. In 1900 the ujiko of Ōyamazumi petitioned for reinstatement, and both shrines with 174 tsubo (about 575 m²) were returned to Naiku. The buildings were rebuilt in March 1924.

The name Koyasu means "child-rearing", and the deity is Konohanasakuya Hime no Mikoto, daughter of Oyamatsumi no Kami and wife of Ninigi no Mikoto, who gave birth to three children amid fire. Visitors hang small torii gates bought at the Tarodaya shop in Ujiurata 1-chome before the altar to pray for easy delivery.

Koyasu Shrine stands inside the Naiku grounds of Ise Jingu, near the Eji watchpost east of the Ujibashi bridge, beside Oyamazumi Shrine. Buses from Ise City Station's south exit or Ujiyamada Station reach Naiku-mae in about 15 minutes; buses from Isuzugawa Station also serve Naiku-mae. The shrine shares its grounds with Oyamazumi Shrine, with Koyasu in front and Oyamazumi behind.

Koyasu Shrine is the 30th of the 30 shokan-sha administered by the Inner Shrine (Naiku) of Ise Jingu, and unlike most of them it has a saisen box. Small torii gates are offered at the altar for safe childbirth; they are sold at Tawaraya in Ujiurata 1-chome. The shrine shares its grounds with Oyamazumi Shrine, which stands just behind it.