Darmian County (Persian: شهرستان درمیان‎) is a county in South Khorasan Province in Iran. The capital of the county is Asadiyeh. It was separated from Birjand County in 2005. At the 2006 census, the county's population was 51,793, in 12,893 families. The county consists of three districts Central District, Qohestan District, and Gazik District.