Kōriyama (郡山市, Kōriyama-shi^?) is a city in the center of the Nakadōri region of Fukushima Prefecture, Japan. As of May 2011, the city had an estimated population of 336,328. The total area is 757 km².

The city was founded on 1 September 1924. It is now designated as a "core city" and functions as a commercial city in Fukushima Prefecture. Kōriyama is the second largest conurbation in the Tōhoku region.

Kōriyama once thrived as a Shukuba town because of its importance as a traffic focal point. Kōriyama was formerly called Asaka(安積). In the Meiji period, the Meiji government had many samurai reclaim the land to help the poor. As a result, Asaka developed into a big food basket and the population grew.

Kōriyama was incorporated as a city on 1 September 1924.

In 1965, the city merged with some nearby towns and villages.

In 1997, the city was designated as a "core city".

On March 11, 2011, Fukushima Daiichi experienced a nuclear disaster, which forced mandatory evacuations of cities within 30km of the nuclear power plant. Koriyama is located approximately 34 miles (55 km) west of Fukushima Daiichi; therefore, it was not included in the evacuation zone, although most people refrained from outdoor activity.