Ersa (French pronunciation: [ɛʁsa]) is a commune of the Haute-Corse department of France on the island of Corsica.

The commune is watered by the streams Acqua Tignese and Granaghjulu on its undulating slopes of the Mount Maghjore (364 m).

When Corse joined France at the end of the 17th century there were 1130 inhabitants, highly involved in the cultivation of grapes for wine.

The ancient small port of Barcaghju, situated at the rear of the bay, near to the mouth of river Acqua Tignose, offers a panorama of the island of Giraglia.

The second sea-front, Tollare, at the mouth of the River Granaghjulu, extends its ancient mansions around that of its chapel Saint-Anne and its round Genoese tower.