| Primero de Mayo Department | |
| Native Name Lang: | es |
| Settlement Type: | Department |
| Mapsize: | 180px |
| Pushpin Map Caption: | Location of Primero de Mayo Department in Argentina |
| Coordinates: | -27.2667°N -116°W |
| Subdivision Type: | Country |
| Subdivision Name: |  Argentina |
| Subdivision Type1: | Province |
| Subdivision Name1: | Chaco Province |
| Seat Type: | Head town |
| Unit Pref: | Metric |
| Area Total Km2: | 1,864 |
| Population Total: | 9,131 |
| Population Density Km2: | auto |
| Timezone1: | ART |
| Utc Offset1: | -3 |
| Postal Code: | H3505 |
| Area Code: | 03722 |
Primero de Mayo is a south eastern department of Chaco Province in Argentina.
The provincial subdivision has a population of about 9,000 inhabitants in an area of 1,864 km2, and its capital city is Margarita Belén, which is located around 1,035 km from the Capital federal.