Atar is a department of the Adrar Region in western Mauritania. The capital lies at Atar. The other villages in the department are Ain Ehel Taya, Tawaz, Azougui and Choum.

20°31′N 13°03′W / 20.517°N 13.050°W / 20.517; -13.050

The Atar constituency covers the same area as the department. In 2018 there were a total of 25,023 registered voters and they own 2 seats in the Mauritanian congress, It is the only constituency in Adrar region to own more than 1 seat in congress.