The Iida Line is a Japanese railway line connecting Toyohashi Station in Toyohashi, Aichi with Tatsuno Station in Tatsuno, Nagano, operated by Central Japan Railway Company. The line links eastern Aichi Prefecture and southern Nagano Prefecture through northwestern Shizuoka Prefecture. It goes through steep mountains as well as cities such as Iida and Ina. The line was originally of four different private railway lines, the first of which opened in 1897.