port city, Nagasaki ken (prefecture), Kyushu, Japan, on the eastern coast of the Shimabara Peninsula, some 40 miles (65 km) east of Nagasaki. The city, which was a castle town of the Matsudaira family, contains the ruins of the Moridake Castle. The city is noted as the site of the Shimabara Rebellion, a peasant uprising that culminated in the slaughter of some 37,000 individuals.

Shimabara is situated near Mount Unzen (Unzen, Mount) (4,462 feet 【1,360 m】), an active volcano that last erupted in 1991. A major eruption of Unzen in 1792 that created the picturesque Tsukumo Islets also caused the deaths of about 15,000 people. The region is known for the production of mandarin oranges, tobacco, and tea and for its hot springs. Pop. (2005) 50,045.