Okayama (岡山市, Okayama-shi^?) is the capital city of Okayama Prefecture in the Chūgoku region of Japan.

The city was founded on June 1, 1889. As of August 2010, the city has an estimated population of 705,224 and a population density of 893 persons per km². The total area is 789.88 km².

The city is the site of Kōraku-en and the black Okayama Castle, which is ranked among the best 100 Japanese castles. The city is famous as the setting of the Japanese fable "Momotarō".

Before the Muromachi period, Okayama was one corner of a farm region and included a small castle built by the Kanemitsu. In the Sengoku period, Ukita Naoie attacked Okayama and attacked the castle for the transportation resources and extensive farmland in the region. Naoie remodeled the castle, built the old Sanyo road to the central part of the castle town, and called in tradesmen both from inside and outside of Bizen province. Okayama became the political and economical capital of Bizen province.

In 1600, Ukita Hideie, who was the son of Naoie and the lord of Okayama, lost at the Battle of Sekigahara. The next year, Kobayakawa Hideaki came to Okayama and became the feudal lord of Okayama Domain. Hideaki died in 1602, however, ending the Kobayakawa line. Ikeda Tadatugu, who was the feudal lord of Himeji Domain, became the next lord of Okayama. After this time, Okayama was ruled by the Ikedas until the latter part of the 19th century. Continuing its economic development, Okayama became one of the ten best large castle towns in Japan in the 18th century. The Korakuen Garden was developed by the fourth feudal lord, Ikeda Tsunamasa.