Uku (宇久町, Uku-machi) was a town located in Kitamatsuura District, Nagasaki Prefecture, Japan. It encompasses the entirety of Ukujima island.

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.

On March 31, 2006, Uku, along with the town of Kosaza (also from Kitamatsuura District), was merged into the expanded city of Sasebo.^[1]

Uku can be accessed by ferry from Fukuoka's Hakata port as well as a number of ferries departing from Sasebo ferry port daily.