was a town located in Minamisaku District, Nagano Prefecture, Japan.
As of January 1, 2004, the town had an estimated population of 8,663. The total area was 122.11 km<sup>2</sup>.
On March 20, 2005, Saku, along with the village of Yachiho (also from Minamisaku District), was merged to create the town of Sakuho.