Martin County is a county located in the U.S. state of Minnesota. As of 2000, the population was 21,802. Its county seat is Fairmont.

According to the U.S. Census Bureau, the county has a total area of 730 square miles (1,890 km²), of which 709 square miles (1,837 km²) is land and 20 square miles (52 km²) (2.77%) is water.

Official Martin County website