Oita (ō´ētä), city (1990 pop. 408,501), capital of Oita prefecture, NE Kyushu, Japan, a port on Beppu Bay. It is a rail hub, a manufacturing center, and a distribution point for agricultural products. It has several oil refineries and petrochemical plants. Oita was an important castle town in the 16th cent. and traded with the Portuguese. Oita prefecture (1990 pop. 1,236,924), 2,447 sq mi (6,338 sq km), is mountainous, rising to 5,850 ft (1,783 m) in Mt. Kuju. Farming, forestry, and industry are the main economic activities. Beppu, a well-known hot springs resort, is an important city. In 1995, a long-dormant volcano located southwest of the capital city erupted.