Norwegian County Road 406 (Fv 406) is a Norwegian county road in Birkenes municipality in Agder county, Norway.

The 18.1-kilometre (11.2 mi) long road runs between the village of Sennumstad on the Tovdalselva river to the village of Stemlona.

[1] The road connects to the Norwegian County Road 405 at Stemlona and it connects to the Norwegian National Road 41 at its other end at Sennumstad.

The road runs through a fairly rural area in Birkenes.

The Sørlandsbanen railway line crosses over the road at Fidje.