Hemsedal is a municipality in Buskerud county, Norway. It is part of the traditional region of Hallingdal. The administrative centre of the municipality is the village of Trøym. In 1897, Hemsedal was separated from the municipality of Gol to become a municipality of its own.
Hemsedal is the second largest Ski resort in Norway. From the museum farm Øvre Løkji, there are several trails up into the mountains.The Old Norse form of the name was Hemsudalr. The first element is the genitive case of a river name Hemsa (now Hemsil) and the last element is dalr which means "valley" or "dale". The meaning of the river name is unknown.