Okagaki (岡垣町, Okagaki-machi) is a town located in Onga District, Fukuoka Prefecture, Japan.

Fukuoka Prefecture Onga has a humid subtropical climate (Köppen Cfa) characterized by warm summers and cool winters with light to no snowfall.

After the Meiji restoration, the villages of Okaken and Yahagi were established with the creation of the modern municipalities system on April 1, 1889.

Okagaki has a mayor-council form of government with a directly elected mayor and a unicameral town council of 13 members.

In terms of national politics, the town is part of the Fukuoka 8th district of the lower house of the Diet of Japan.