Eight of the remains are dated to between 50,000 and 68,000 years ago, the ministry said in a statement.
But the oldest is from much earlier – between 90,000 and 100,000 years ago.
Neanderthals, the closest ancient relatives of humans, died out about 40,000 years ago.
It is unclear what killed them off, though theories include an inability to adapt to climate change and increased competition from modern humans.
The find occurred in the Grotta Guattari, a prehistoric cave that was discovered more than 80 years ago in the town of San Felice Circeo, around 80 kilometres south of the Italian capital.
“Together with two others found in the past on the site, they bring the total number of individuals present in the Guattari Cave to 11, confirming it as one of the most significant sites in the world for the history of Neanderthal man,” the ministry said.
Culture Minister Dario Franceschini hailed the find as “an extraordinary discovery which the whole world will be talking about”.
The findings follow new research begun in October 2019 into the Guattari Cave, which was found by accident by a group of workers in February 1939.
On visiting the site shortly afterwards, paleontologist Albert Carlo Blanc made a stunning find – a well-preserved skull of a Neanderthal man.
The cave had been closed off by an ancient landslide, preserving everything inside as a snapshot in time that is slowly offering up its secrets.
Recent excavations have also found thousands of animal bones, notably those of hyenas and the prey they are believed to have brought back to the cave to eat or store as food.
There are remains of large mammals including elephant, rhinoceros, giant deer, cave bear, wild horses and aurochs – extinct bovines.
