Seljord is a municipality in Telemark county, Norway. It is part of the traditional region of Vest-Telemark. The administrative centre of the municipality is the village of Seljord. The parish of Siljord was established as a municipality on 1 January 1838 .
Seljord is famous for its sea serpent, Selma, who allegedly lives in Lake Seljord .The yearly Dyrsku'n market, held since 1866, attracts 60-80,000 visitors each year.The municipality is named after the old Seljord farm , since the first church was built there. The first element is the genitive case of selja which means "sallow-tree" or "willow" and the last element is gerði which means "field". Prior to 1889, the name was written "Silgjord" or "Sillejord".