Kōshū or Koshu may refer to:

Kōshū, another name for Kai Province. Kōshū, Yamanashi, the present city in Yamanashi Prefecture. Koshu (grape), a variety of Grape. / 甲州 (葡萄)

Kōshū, another name for Hyūga Province.

Kōshū (survey ship), a ship of the Imperial Japanese Navy