The Mogami River (最上川, Mogami-gawa) is a river in Yamagata Prefecture, Japan.
It is 224 km long and has a watershed of 7,040 km². It is regarded as one of the three most rapid rivers of Japan (along with the Fuji River and the Kuma River).
The river rises from southern Yamagata Prefecture and flows to the north, and turns west at Shinjō and flows into the Sea of Japan at Sakata. Water transportation once flourished on the river and carried local products such as safflowers and rice to the Kansai region.