| Magta Lahjar | |
| Settlement Type: | Commune and town |
| Pushpin Map: | Mauritania |
| Pushpin Label Position: | bottom |
| Pushpin Mapsize: | 300 |
| Pushpin Map Caption: | Location in Mauritania |
| Subdivision Type: | Country |
| Subdivision Name: |  Mauritania |
| Subdivision Type1: | Region |
| Subdivision Name1: | Brakna |
| Subdivision Type2: | Department |
| Leader Title: | Mayor |
| Leader Name: | Moussa O/ Cheikh Ahmedou (PRDS) |
| Unit Pref: | Imperial |
| Area Total Km2: | 693.7 |
| Population As Of: | 2013 census |
| Population Total: | 18,616 |
| Population Urban: | 12,498 |
| Population Density Km2: | auto |
| Population Blank1 Title: | Ethnicities |
| Timezone: | GMT |
| Utc Offset: | +0 |
| Coordinates: | 17.4483°N -13.1389°W |
Magta Lahjar is a town and commune in the Brakna Region of southern Mauritania.[1]
In 2013, it had a population of 18,616.[2] [3]