ken (prefecture), central Honshu, Japan, on the Pacific coast. More than half of its area lies within the Nōbi Plain and two smaller plains to the east. The northwestern border with Gifu prefecture is formed by the Kiso River, sometimes known as the Nihon (Japan) Rhine. The irregular coast is marked by the peninsulas of Chita (west) and Atsumi (east), which enclose Mikawa Bay and lie within Mikawa Bay Quasi-national Park, a popular resort area.

During the Tokugawa era (1603–1867) the area that is now Aichi prefecture was Japan's centre for cotton cultivation and manufacture. Its capital, Nagoya, and surrounding industrial suburbs now constitute the Chūkyō Industrial Zone, Japan's second-ranking industrial concentration after Keihin (Tokyo-Yokohama Region). Textiles, steel, ceramics, automobiles, machinery, plywood, chemicals, cloisonné, and processed foods are produced. Toyohashi is a major cotton and silk textile centre, and Seto is noted for its china. There are well-developed road and rail services; main port facilities are in Nagoya. Area 1,984 square miles (5,139 square km). Pop. (1990) 6,691,000; (1994 est.) 6,819,000.