| Official Name: | Siadak |
| Native Name: | سيادك |
| Settlement Type: | village |
| Pushpin Map: | Iran |
| Mapsize: | 150px |
| Subdivision Type: | Country |
| Subdivision Type1: | Province |
| Subdivision Name1: | Sistan and Baluchestan |
| Subdivision Type2: | County |
| Subdivision Name2: | Hirmand |
| Subdivision Type3: | Bakhsh |
| Subdivision Name3: | Central |
| Subdivision Type4: | Rural District |
| Subdivision Name4: | Margan |
| Population As Of: | 2006 |
| Population Total: | 115 |
| Population Density Km2: | auto |
| Timezone: | IRST |
| Utc Offset: | +3:30 |
| Timezone Dst: | IRDT |
| Utc Offset Dst: | +4:30 |
| Coordinates: | 31.115°N 61.745°W |
Siadak (Persian: سيادك, also Romanized as Sīādak and Sīyādak; also known as Seyāhdak, Sīāhdag, and Sīāhdak) is a village in Margan Rural District, in the Central District of Hirmand County, Sistan and Baluchestan Province, Iran. At the 2006 census, its population was 115, in 31 families.