Ōkawa (大川市 Ōkawa-shi) is a city located in Fukuoka Prefecture, Japan. The city was founded on April 1, 1954. The name means 'big river'.
As of January 31, 2012, the city has an estimated population of 37,579, with 13,102 households and a population density of 1,117.42 persons per km². The total area is 33.63 km².
Ōkawa is located in southern Fukuoka Prefecture next to the border with Saga Prefecture. The Chikugo River flows from northeast to southwest through the city, which is relatively flat. At the centre of Ōkawa, the Hanamune River flows into the Chikugo River as a tributary.