Eureka Township is one of the seventeen townships of Adair County, Iowa, United States.

is said to have exclaimed by an early settler when he discovered coal within the township borders.

[3] It was served by Berea post office from 1894 to 1908,[4] named after the Ancient Greek city of Berea.

[5] According to the United States Census Bureau, Eureka Township covers an area of 35.59 square miles (92.19 square kilometers); of this, 0.05 square miles (0.13 square kilometers) or 0.14 percent is water.

The township contains one cemetery, Eureka.