Iwaki (いわき市, Iwaki-shi) is a city located in the southern part of the Hamadōri coastal region of Fukushima Prefecture, Japan.
A designated core city, Iwaki is also one of the growing number of hiragana cities. Its total area is 1,231.35 km², making it the 10th largest city in Japan (2010). Its estimated population as of May 2011 is 337,288, making it the biggest city of the prefecture. Iwaki has a population density of 270 persons per km².
The present "Iwaki City" started as the merger of 14 municipalities on October 1, 1966. The city was the third hiragana city, following Chino, Nagano and Mutsu, Aomori. The area was the largest in Japan at the time. The city works as an industrial hub of Tōhoku region, and is rich in sightseeing resources. As of 2005, about 7.6 million sightseers visit the city a year. Every year Iwaki hosts the Taira Tanabata Festival from 6–8 August.