| San Martín de Zar | |
| Official Name: | San Martín Zar |
| Settlement Type: | Minor local entity |
| Pushpin Map: | Spain Province of Burgos#Spain Castile and León#Spain |
| Pushpin Label: | San Martín de Zar |
| Pushpin Label Position: | left |
| Subdivision Type: | Country |
| Subdivision Type1: | Autonomous community |
| Subdivision Type2: | Province |
| Subdivision Name2: | Province of Burgos |
| Subdivision Type3: | Municipality |
| Subdivision Name3: | Condado de Treviño |
| Population Total: | 5 |
| Coordinates: | 42.6947°N -2.7267°W[1] |
| Elevation M: | 656 |
| Postal Code Type: | Postal code |
San Martín de Zar or San Martín Zar is a hamlet and minor local entity located in the municipality of Condado de Treviño, in Burgos province, Castile and León, Spain. As of 2020, it has a population of 5.[2]
San Martín de Zar is located 110 km east-northeast of Burgos.