The plane crashed in July last month, but a French ship today picked up signals in a five km area where the plane is thought to have come down.
The French ship, named La Place, has three deep-water devices known as Detector 6000s, which it used to detect signals.
"The signal from a beacon from a flight recorder has been detected," said Remi Jouty of France's Bureau of Investigations and Analysis, the BBC reported.
There were 66 people on board wen the Airbus crashed just weeks ago, after the plane vanished just as it moved from Greek to Egyptian airspace control. Greece said it had swerved radically and plunged from 37,000 feet to 15,000 before disappearing from radar screens.
The Cairo bound plane had taken off from Paris at 11.09pm local time on Thursday. It was due to land at Cairo shortly after 3am local time. The pilot had 2,766 flying hours; the aircraft was manufactured in 2003 and had routine maintenance checks carried out in Cairo on Wednesday.
Debris and human remains have already been recovered.
It's still uncertain what caused the crash, which is why finding the black box is so crucial. Terrorism has not been ruled out.
In March, an Egyptair plane bound for Cairo was hijacked and diverted to Cyprus. All hostages were later released unharmed.
And last October a Russian plane flying from Sharm el-Sheikh crashed killing 224 passengers.