| Marsjøen | |
| Pushpin Map: | Innlandet#Norway |
| Pushpin Label Position: | bottom |
| Pushpin Map Caption: | Location of the lake |
| Coordinates: | 62.3514°N 10.0644°W |
| Location: | Folldal Municipality, Innlandet |
| Catchment: | 23.39km2 |
| Basin Countries: | Norway |
| Area: | 2.64km2 |
| Reference: | NVE[1] |
Marsjøen is a lake in Folldal Municipality in Innlandet county, Norway. The 2.64km2 lake lies in the northern part of the municipality, about east of the larger lake Fundin. There is a dam at the south end of the lake which is used to regulate the water height for use in the nearby Einunna and Savalen hydro-electric power stations.