Usui (碓井町 Usui-machi) was a town located in Kaho District, Fukuoka, Japan.
On March 27, 2006 Usui was merged with the towns of Inatsuki and Kaho, all from Kaho District, and the old city of Yamada, to form the new city of Kama.
As of 2003, the town had an estimated population of 6,287 and a density of 744.02 persons per km². The total area was 8.45 km².