Nagasaki, city in Japan on western Kyushu, capital of Nagasaki Prefecture. The city is at the head of Nagasaki Bay, which is about 5 km (3 mi) long, sheltered on all sides, and one of the best natural harbours in Japan. Nagasaki has important coal-mining and fishing industries, shipyards, steelworks, and plants manufacturing electrical equipment. It is the site of Nagasaki University (1949).

On August 9, 1945, a United States Air Force plane released an atomic bomb on Nagasaki. About one-third of the city was destroyed, and some 66,000 people were killed or injured. This was three days after the first atomic bomb destroyed Hiroshima. A memorial in Nagasaki marks the location over which the bomb exploded. Population 452,064 (2007).