Ballon-Saint Mars () is a commune in the department of Sarthe, western France. The municipality was established on 1 January 2016 by merger of the former communes of Ballon and Saint-Mars-sous-Ballon.
The creation of the new commune of ëBallon-Saint Marsû was decided by a vote of the municipal councils of the communes of Ballon and Saint-Mars-sous-Ballon on 25 June 2015, after several months of negotiations.
Population data refer to the area corresponding with the commune as of January 2025.