| Montoir-de-Bretagne | |
| Native Name: | (Gallo) |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason ville fr Montoir-de-Bretagne (Loire-Atlantique).svg |
| Arrondissement: | Saint-Nazaire |
| Canton: | Saint-Nazaire-2 |
| Insee: | 44103 |
| Postal Code: | 44550 |
| Mayor: | Thierry Noguet[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | CA Région Nazairienne et Estuaire |
| Coordinates: | 47.3292°N -2.1478°W |
| Elevation Min M: | 0 |
| Elevation Max M: | 15 |
| Area Km2: | 36.79 |
Montoir-de-Bretagne (in French pronounced as /mɔ̃twaʁ də bʁətaɲ/, literally Montoir of Brittany; Gallo: Montoér or Montouèrr, Breton: Mouster-al-Loc'h) is a commune in the Loire-Atlantique department in western France.
The population data given in the table below refer to the commune of Montoir-de-Bretagne in its geography at the given years. In 1913 the commune of Trignac was created from part of Montoir-de-Bretagne, in 1925 Saint-Malo-de-Guersac was created from part of Montoir-de-Bretagne.