Andreiașu de Jos is a commune located in Vrancea County, Muntenia, Romania. It is composed of seven villages: Andreiașu de Jos, Andreiașu de Sus, Arșița, Fetig, Hotaru, Răchitașu, and Titila.

The commune is located in a hilly area, at the foot of the Curvature Carpathians, on the left bank of the Milcov River, the traditional boundary between Wallachia and Moldavia.