It was excavated from a cave in western Sri Lanka. Officials say they will send it for carbon-dating and expect results in a month.
Other items, excavated from the same layer as the skeleton, have been confirmed as dating back 37,000 years.
Stone and bone tools were found with the skeleton.
The skeleton - thought to be homo sapiens - was found in Fa Hien Cave in the district of Kalutara, Western Province, Sri Lanka.
Human remains were also discovered at the cave in the 1960s and 1980s.
Archaeologist Nimal Perera told the Sri Lankan Daily News that the find - made a few days ago - proves that homo sapiens settled in Sri Lanka about 40,000 years ago.
He said the find is the first time that a complete pre-historic human skeleton has been unearthed in Sri Lanka, and more evidence is currently being unearthed about its eating habits, rituals and equipment made out of stone.
Some ornaments made of beads have also been excavated, as have weapons made of animal bone, Dr Perera said.
Sources: BBC & Dailynews