Mont-d'Astarac (French pronunciation: [mɔ̃ dastaʁak]; Gascon: Lo Mont d'Astarac) is a commune in the Gers department in southwestern France.

Its history goes back to the 930s, when it became the first capital of Astarac. It was on the feudal motte, still visible today, that Arnaud Garcia established his castle, having inherited the County of Astarac from his father Count de Gascogne, Garcia Sanchez (called the Crooked), grandson of the count of Castille. It is worth seeing for its monuments - tower and church - registered among the Historic Monuments of France, and for its beautiful murals dating to the 15th century.

Historical population

Year	Pop.	±%
1962	132	—
1968	122	−7.6%
1975	107	−12.3%
1982	112	+4.7%
1990	103	−8.0%
1999	102	−1.0%
2008	96	−5.9%

• Communes of the Gers department