Okayama Prefecture (岡山県, Okayama-ken^?) is a prefecture of Japan located in the Chūgoku region on Honshu island. The capital is the city of Okayama.

During the Meiji Restoration, the area of Okayama Prefecture was known as Bitchū Province, Bizen Province and Mimasaka Province.

Okayama Prefecture borders Hyōgo Prefecture, Tottori Prefecture and Hiroshima Prefecture. It faces Kagawa Prefecture in Shikoku across the Seto Inland Sea and includes 90 islands in the sea.

Okayama Prefecture is home to the historic town of Kurashiki. Most of the population is concentrated around Kurashiki and Okayama. The small villages in the northern mountain region are aging and declining in population - more than half of the prefectures municipalities are officially designated as depopulated.

Fifteen cities are located in Okayama Prefecture:

Towns and villages in each district:

The sports teams listed below are based in Okayama.

Some tourist attractions are:

Coordinates: 34°42′N 133°51′E / 34.7°N 133.85°E / 34.7; 133.85