Norddorf auf Amrum (Öömrang: Noorsaarep üüb Oomram, Danish: Nordtorp) is a municipality on the island of Amrum in the district of Nordfriesland in Schleswig-Holstein, Germany.
Together with Süddorf, Norddorf is the oldest village of the island. In 1890, Friedrich von Bodelschwingh founded a number of seaside hospices in Norddorf proper and north of it. Due to this, the place developed into a seaside resort. In 1925, great parts of the village were destroyed by a fire, so today's view of the village is dominated by mostly modern houses without thatched roofs. Today, the hospices are not existent any longer or they now serve other purposes.
During the early 20th century, the so-called Kniephafen harbour existed north of Norddorf at Amrum's vast Kniepsand beach. The port was navigable by greater vessels and it most of all served the nautical traffic between Amrum and the port of Hörnum on the neighbouring island of Sylt. The Kniephafen was linked to the network of Amrum's island railway. In 1938, the pier was last moved further north due to proceeding aggradation. With the adjoining of the Kniepsand beach to the belt of dunes on Amrum's western shore, the harbour had to be abandoned.