| Official Name: | Järnforsen |
| Pushpin Map: | Sweden Kalmar#Sweden |
| Subdivision Type: | Country |
| Subdivision Name: | Sweden |
| Subdivision Type3: | Municipality |
| Subdivision Name3: | Hultsfred Municipality |
| Subdivision Type2: | County |
| Subdivision Name2: | Kalmar County |
| Subdivision Type1: | Province |
| Subdivision Name1: | Småland |
| Area Footnotes: | [1] |
| Area Total Km2: | 1.35 |
| Population As Of: | 31 December 2010 |
| Population Total: | 489 |
| Population Density Km2: | 363 |
| Timezone: | CET |
| Utc Offset: | +1 |
| Timezone Dst: | CEST |
| Utc Offset Dst: | +2 |
| Coordinates: | 57.4167°N 52°W |
Järnforsen is a locality situated in Hultsfred Municipality, Kalmar County, Sweden, with a population of 489 in 2010.
South of Järnforsen, in Slättemossa, there is a deposit of orbicular granite.