Kohanabad District (Persian: بخش کهن آباد) is a district (bakhsh) in Aradan County, Semnan Province, Iran. At the 2006 census, its population was 4,745, in 1,392 families. The District has no cities. The District has two rural districts (dehestan): Faravan Rural District and Kohanabad Rural District. The District was established in 2011, along with Aradan County.