San Tomaso Agordino (Ladin: San Tomas) is a comune (municipality) in the Province of Belluno in the Italian region Veneto, located about north of Venice and about northwest of Belluno. As of 31 December 2004, it had a population of 766 and an area of .
The municipality of San Tomaso Agordino contains the frazione (subdivision) Pecol.
San Tomaso Agordino borders the following municipalities: Alleghe, Cencenighe Agordino, Rocca Pietore, Taibon Agordino, Vallada Agordina.
San Tomaso Agordino is twinned with: