The Yonesaka Line is a railway line in Japan, operated by East Japan Railway Company. It connects Yonezawa Station in Yamagata Prefecture to Sakamachi Station in Niigata Prefecture. At Yonezawa, connections to the Yamagata Shinkansen and Ōu Main Line can be made; while the Uetsu Main Line connects at Sakamachi Station. The line takes its name from the first kanji of Yonezawa (米沢) and Sakamachi (坂町).

The East Japan Railway Company is a major passenger railway company in Japan, the largest of the seven Japan Railways Group companies. The company name is officially abbreviated as JR-EAST or JR East in English, and as JR Higashi-Nihon in Japanese. The company's headquarters are in Yoyogi, Shibuya, Tokyo, next to Shinjuku Station. It is listed in the Tokyo Stock Exchange, is a constituent of the TOPIX Large70 index, and is one of three Japan Railways Group constituents of the Nikkei 225 index, the others being JR Central and JR West.