Frederikshavn (originally named Fladstrand) is a municipality (Danish, kommune) in North Jutland County on the northeast coast of the Jutland peninsula in northern Denmark. Its name translates to "Frederik's harbour". The municipality covers an area of 180 km², and has a total population of 33,975 (2005). Its mayor is Erik Sørensen, a member of the Social Democrats (Socialdemokraterne) political party. The main town and the site of its municipal council is the city of Frederikshavn.
Neighboring municipalities are Skagen to the north, Sindal to the west, and Sæby to the south. To the east are the waters of Ålbæk Bay (Ålbæk Bugt) in the north and the Læsø Channel (Læsø Rende), the strait that separates Jutland from the Danish island of Læsø, in the south. Beyond these lie the Kattegat, the strait that separates Denmark from Sweden.
Frederikshavn has, like the rest of North Jutland, been hit with hard unemployment. The city's largest workplace, the shipyard Danyard, closed in the late 1990s. This resulted in more than 2,000 workers being unemployed. Today there is still activity at the large ship building area, with many small companies renting space there.