| San Martín | |
| Native Name: | Departamento San Martín |
| Settlement Type: | Department |
| Coordinates: | -33.0667°N -87°W |
| Subdivision Type: | Country |
| Subdivision Name: | Argentina |
| Established Title: | Established |
| Established Date: | December 20, 1816 |
| Founder: | ? |
| Seat Type: | Seat |
| Seat: | San Martín |
| Leader Title: | Mayor |
| Leader Name: | Raúl Rufeil |
| Unit Pref: | Metric |
| Area Total Km2: | 1,504 |
| Population Total: | 108,448 |
| Population Density Km2: | auto |
| Population Demonym: | sanmartiniano/a |
| Postal Code Type: | Postal Code |
| Postal Code: | M5570 |
| Postal2 Code Type: | IFAM |
| Postal2 Code: | MZA014 |
| Area Code Type: | Area Code |
| Area Code: | 0263 |
| Blank Name Sec1: | Patron saint |
| Blank Info Sec1: | ? |
San Martín is a department located in the centre of Mendoza Province in Argentina.
The provincial subdivision has a population of about 108,500 inhabitants in an area of, and its capital city is San Martín, which is located around from the Capital federal.
The Department and its cabecera (capital) are named in honour of General San Martín (1778-1850), the military leader that led the Argentine forces to victory over the Spanish Empire during the Argentine War of Independence.
The city of San Martín is home to Atlético Club San Martín, a football club currently playing in the regionalised 4th Division.