Kōshū (甲州市, Kōshū-shi) is a city located in Yamanashi Prefecture, Japan.

The city is the home of the indigenous Koshu grape and is synonymous with viticulture and wine production in Japan.

Kōshū is in northeastern Yamanashi Prefecture, occupying the eastern portion of the Kofu Basin.

During the Edo period, all of Kai Province was tenryō territory under direct control of the Tokugawa shogunate.

Kōshū has a mayor-council form of government with a directly elected mayor and a unicameral city legislature of 18 members.