Ichihara, city, western Chiba ken (prefecture), east-central Honshu, Japan. It lies on the east coast of Tokyo Bay, just south of Chiba city.
The city of Ichihara was formed in 1962 by amalgamation of the towns of Ichihara, Goi, Sanwa, Shizu, and Anegasaki. Except for the trade centre and railway station of Goi, the towns’ economies before World War II were based on agriculture and fishing. Agriculture declined in relative importance after the war, as manufacturing rose in prominence. Ichihara is part of the Keihin Industrial Zone that encompasses the Tokyo-Yokohama metropolitan area. Its coastal area has been reclaimed for use by oil refineries, petrochemical and steel plants, and shipyards. In March 2011 shaking caused by a severe earthquake off the northeast coast of Honshu sparked a massive fire in storage tanks at a refinery that took more than a week to fully extinguish. Pop. (2005) 280,255; (2010) 280,416.