Pallars Jussà (Catalan pronunciation: [paˈʎa(ɾ)z dʒuˈsa]) is a comarca (county) in Alt Pirineu, Catalonia, Spain.

It was established as a comarca in 1936, out of the old county of Pallars.

The name is an archaism meaning "Lower Pallars";[1] to the northeast and into the mountains is Pallars Sobirà.

Its capital and largest municipality is Tremp.