Lardal is a municipality in Vestfold county, Norway. The administrative centre of the municipality is the village of Svarstad. The parish of Laurdal was established as a municipality on 1 January 1838 (see formannskapsdistrikt). The municipality is divided into the parishes of Svarstad, Styrvoll, and Hem.The Old Norse form of the name was Lagardalr. The first element is the genitive case of lögr meaning "water" or "river" (here the Numedalslågen river). The last element is dalr which means "valley" or "dale". Prior to 1889, the name was spelled "Laurdal".