The Tōhoku Main Line is a 575.7-kilometre-long (357.7 mi) railway line in Japan operated by the East Japan Railway Company. The line starts from Tokyo Station in Chiyoda, Tokyo and passes through such cities as Saitama, Utsunomiya, Fukushima, and Sendai, before reaching the end of the line in Morioka. The line originally extended to Aomori, but was truncated upon the extension of the Tōhoku Shinkansen beyond Morioka, which mostly parallels the Tōhoku Main Line. A portion of the Tōhoku Main Line is also shared with the Keihin–Tōhoku Line and the Saikyō Line.

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.