| Country: | NOR |
| Type: | Fylkesvei |
| Route: | 405 |
| Image Notes: | View of the road near Mosby, Norway |
| Map Custom: | yes |
| Length Km: | 54.56 |
| Direction A: | North |
| Terminus A: | Engesland, Birkenes |
| Direction B: | South |
| Terminus B: | Mosby, Kristiansand |
| Previous Type: | fylkesvei |
| Previous Route: | 404 |
| Next Type: | fylkesvei |
| Next Route: | 406 |
Norwegian County Road 405 (Fv405) is a Norwegian county road which runs between from the village of Engesland in Birkenes municipality in Agder county in the north to the junction with the Norwegian National Road 9 in the village of Mosby in Kristiansand municipality in the south. The road is long.[1] [2] Prior to a 2010 government reform, the road was classified as a Norwegian national road.