The Pope, who is the first Latin American one, will participate Roman Catholic World Youth Day festival, which is organized by the Vatican in every two years in different cities of the world.
Pope Francis came to Rome's biggest international airport, Leonardo Da Vinci, from the Vatican by Italian state-owned helicopter. The Pope flew to Rio de Janeiro at 08.52 local time.
The Italian Premier Enrico Letta saw the Pontiff off at the airport where high security precautions have been taken.
The Pope carried his own bag and he prefered regular first class accommodation rather than a flat-bed suite.
Pope Francis's way to Rio de Janeiro will last 12 hours. He is expected to land at 17.00 local time.
The Catholic World Youth Day festival is celebrated since 1984. Millions of youth come together with the spiritual leader of the Catholic world in the festival.