Kiso District

 is a district located in Nagano Prefecture, Japan.
As of November 1, 2005, the district has an estimated population of 34,759. The total area is 1,546.26 km2.
Historically, the district was once known as Nishichikuma District (西筑摩郡) until May 1, 1968.
There are only three towns and three villages within the district.