A small municipality in the county of Buskerud in Norway. Rollag lies in the heart of Numedal valley, the westernmost valley in south-eastern Norway. The river Numedalslågen flows through Rollag and into the Ytre Oslofjord at Larvik.
Rollag has circa 1400 inhabitants. The civic center is the village of Rollag, but there is another village in the municipality too, called Veggli. Rollag is bordered in the north by Nore og Uvdal, in the east by Sigdal, in the south by Flesberg, and in the west by Tinn and the county of Telemark.