Usu (有珠郡 Usu-gun?) is a district located in Iburi Subprefecture, Hokkaido, Japan. As of March, 2008, the district has an estimated Population of 3,009 and a density of 14.7 persons/km². The total area is 205.04 km².
The district has only one town.
Coordinates: 42°34′23″N 140°56′46″E / 42.573°N 140.946°E