Ōi is a town located in Fukui Prefecture, Japan. As of 1 June 2018, the town had an estimated population of 8,102 and a population density of 63 persons per km2. The total area of the town was 212.19 square kilometres (81.93 sq mi). It is one of the few Hiragana towns in Japan.

Fukui Prefecture is a prefecture of Japan located in the Chūbu region of Honshū. Fukui Prefecture has a population of 778,943 and has a geographic area of 4,190 km2. Fukui Prefecture borders Ishikawa Prefecture to the north, Gifu Prefecture to the east, Shiga Prefecture to the south, and Kyoto Prefecture to the southwest.