Henry County is a county located in the U.S. state of Virginia. As of the 2020 census, the population was 50,948. The county seat is usually identified as Martinsville; however, the administration building (where county offices are located and where the board of supervisors holds meetings), county courthouse, and Henry County Sheriff's Office are located on Kings Mountain Road (SR 174) in Collinsville.The Henry County Adult Detention Center is located on DuPont Road in Martinsville. Henry County is part of the Martinsville, VA Micropolitan Statistical Area.