These new power staions would be set up to replace the ones that were closed following the Chernobyl nuclear accident in 1986.
Italy, since then, has had to import its electricity and is the biggest importer of this power in the world.
Mr Berlusconi's government that came to power last May came up with plans to build nuclear power stations to help cut down the country's need to get its power from outside.
President Sarkozy and the Italian PM signed their new nuclear co-operation deal in front of television cameras.
The leader of France explained that his government was putting forward "an unlimited partnership" with Italy with a focus on producing energy that was clean.
