| La Plaine-sur-Mer | |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason ville 44 La Plaine-sur-Mer.svg |
| Arrondissement: | Saint-Nazaire |
| Canton: | Pornic |
| Insee: | 44126 |
| Postal Code: | 44770 |
| Mayor: | Séverine Marchand[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | CA Pornic Agglo Pays de Retz |
| Coordinates: | 47.1333°N -2.1667°W |
| Elevation Min M: | 0 |
| Elevation Max M: | 38 |
| Area Km2: | 16.39 |
La Plaine-sur-Mer (in French pronounced as /la plɛn syʁ mɛʁ/; Breton: Plaen-Raez) is a commune in the Loire-Atlantique department in western France.