Wigtownshire or the County of Wigtown is one of the historic counties of Scotland, covering an area in the south-west of the country. Until 1975, Wigtownshire was an administrative county used for local government. Since 1975 the area has formed part of Dumfries and Galloway for local government purposes. Wigtownshire continues to be used as a territory for land registration, being a registration county. The historic county is all within the slightly larger Wigtown Area, which is one of the lieutenancy areas of Scotland and was used in local government as the Wigtown District from 1975 to 1996.

The shires of Scotland, or counties of Scotland, are historic subdivisions of Scotland established in the Middle Ages and used as administrative divisions until 1975. Originally established for judicial purposes, from the 17th century they started to be used for local administration purposes as well. The areas used for judicial functions (sheriffdoms) came to diverge from the shires, which ceased to be used for local government purposes after 1975 under the Local Government (Scotland) Act 1973.