Sannae-myeon is a myeon or a township in the subdivision of Gyeongju City, North Gyeongsang province, South Korea. As of July 2024, it has a population of 3,203 and covers an area of 142.55 square kilometers.
Located approximately 26 kilometers southwest of central Gyeongju, Sannae-myeon is a mountainous area, with elevations ranging from 200 to 550 meters above sea level. About 83% of the land is classified as forest. It borders Sangbuk-myeon of Ulju-gun, Ulsan to the south, Naenam-myeon of Gyeongju to the southeast, Unmun-myeon of Cheongdo County to the west, and Bukan-myeon of Yeongcheon to the north.
The Dongchangcheon stream flows through the township and eventually feeds into the Unmun Dam, a major water source for Daegu. Due to its mountainous environment, the area supports a variety of freshwater fish species, including lenok, Korean bullhead, minnows, and pond smelt.
Sannae-myeon is further divided into the following ri (administrative divisions):