Uku (宇久町 Uku-machi) was a town located in Kitamatsuura District, Nagasaki, Japan.
On March 1, 2006 Uku, along with the town of Kosaza, also from Kitamatsuura District, was merged into the expanded city of Sasebo.
As of 2003, the town had an estimated population of 3,560 and a density of 134.85 persons per km2. The total area was 26.40 km².
Uku can be accessed by ferry from Fukuoka's Hakata port as well as a number of ferries departing from Sasebo ferry port daily.