The Sado Kokubun-ji (佐渡国分寺) is a Shingon sect Buddhist temple located in the city of Sado, Niigata, Japan. Its honzon is Yakushi Nyōrai. It is the successor to the Nara period kokubunji National Temples established by Emperor Shōmu for the purpose of promoting Buddhism as the national religion of Japan and standardising control of the Yamato rule to the provinces. The archaeological site with the ruins of the ancient temple grounds for the provincial temple was designated as a National Historic Site in 1929.
Shingon Buddhism (真言宗, Shingon-shū) is one of the major schools of Buddhism in Japan and one of the few surviving Vajrayana lineages in East Asia, originally spread from India to China through traveling monks such as Vajrabodhi and .