Hjartdal is a municipality in Telemark county, Norway. It is part of the traditional region of Øst-Telemark. The administrative centre of the municipality is the village of Sauland. The parish of Hjertdal was established as a municipality on 1 January 1838 (see formannskapsdistrikt). It consists of three small communities: Hjartdal, Sauland, and Tuddal.