The two crew members ejected and survived uninjured.
The Mirage was flying back last evening from a mission in Mali, where the French army has been fighting jihadist groups, and crashed half-way between Gao in Mali's restive north and the Niger capital Niamey, where France has a military base.
"The crew was forced to eject following a technical failure," said French military spokesman Gilles Jaron.
"The pilot and navigator were retrieved safe and sound."
France sent troops to Mali in January 2013 to combat Islamist groups who had seized control of much of the vast desert north of the country. Around 1,600 French troops are still engaged in operations there.