| Official Name: | Muijin |
| Native Name: | موييجين |
| Settlement Type: | village |
| Pushpin Map: | Iran |
| Mapsize: | 150px |
| Subdivision Type: | Country |
| Subdivision Type1: | Province |
| Subdivision Name1: | Hamadan |
| Subdivision Type2: | County |
| Subdivision Name2: | Hamadan |
| Subdivision Type3: | Bakhsh |
| Subdivision Name3: | Central |
| Subdivision Type4: | Rural District |
| Subdivision Name4: | Alvandkuh-e Gharbi |
| Population As Of: | 2006 |
| Population Total: | 1,759 |
| Population Density Km2: | auto |
| Timezone: | IRST |
| Utc Offset: | +3:30 |
| Timezone Dst: | IRDT |
| Utc Offset Dst: | +4:30 |
| Coordinates: | 34.8197°N 48.3994°W |
Muijin (Persian: موييجين, also Romanized as Mū’ījīn and Moo’ijin; also known as Hū’ī Jīn, Marījīn, Mū’īn, and Mū’jīn) is a village in Alvandkuh-e Gharbi Rural District, in the Central District of Hamadan County, Hamadan Province, Iran. At the 2006 census, its population was 1,759, in 434 families.