| Official Name: | Shamushak-e Sofla |
| Native Name: | شموشك سفلي |
| Settlement Type: | village |
| Pushpin Map: | Iran |
| Mapsize: | 150px |
| Subdivision Type: | Country |
| Subdivision Type1: | Province |
| Subdivision Name1: | Golestan |
| Subdivision Type2: | County |
| Subdivision Name2: | Gorgan |
| Subdivision Type3: | Bakhsh |
| Subdivision Name3: | Central |
| Subdivision Type4: | Rural District |
| Subdivision Name4: | Roshanabad |
| Population As Of: | 2006 |
| Population Total: | 882 |
| Population Density Km2: | auto |
| Timezone: | IRST |
| Utc Offset: | +3:30 |
| Timezone Dst: | IRDT |
| Utc Offset Dst: | +4:30 |
| Coordinates: | 36.7772°N 54.2725°W |
Shamushak-e Sofla (Persian: شموشك سفلي, also Romanized as Shamūshak-e Soflá; also known as Shamūshak-e Pā’īn) is a village in Roshanabad Rural District, in the Central District of Gorgan County, Golestan Province, Iran. At the 2006 census, its population was 882, in 218 families.