The Rosfjord or Rosfjorden is a fjord in Lyngdal municipality in Agder county, Norway.

The 12-kilometre (7.5 mi) long fjord runs from the town of Lyngdal to the North Sea in the south.

The area surrounding the fjord was once part of the municipality of Austad from 1909 until its dissolution in 1963.

[1] The northern end of the fjord is the location of the Agnefest harbour, a deep water harbour which dates back to at least 1771.

[2] Because of the high salinity of the water, the fjord rarely freezes, making it a suitable harbour.