| Loisy-sur-Marne | |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason ville fr Loisy-sur-Marne 51.svg |
| Arrondissement: | Vitry-le-François |
| Canton: | Vitry-le-François-Champagne et Der |
| Insee: | 51328 |
| Postal Code: | 51300 |
| Mayor: | Romain Desanlis[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | Vitry, Champagne et Der |
| Coordinates: | 48.7589°N 4.5456°W |
| Elevation M: | 98 |
| Area Km2: | 14.07 |
Loisy-sur-Marne (pronounced as /fr/, literally Loisy on Marne) is a commune in the Marne department in north-eastern France.