Roberto Pinotti, 72, said the otherworldly visitor, who wore dark shades to cover his eyes, let two of them on board his flying saucer.
The strange encounter allegedly happened in Francavillia, on the Adriatic Coast, in October 1957.
Dr Pinotti said a group of residents were regularly visited by human-like extraterrestrials who wanted to be “friends” with mankind – just like ET in Steven Spielberg’s Close Encounter movie.
Two men were allowed to enter the UFO to take photographs.
The diameter of the UFO was 24 metres, and the control cabin was 10 metres, they claimed.
The grainy black and white snaps first appeared in a book called “Sono Extraterrestri” by the Italian consul Alberto Perego in 1958 but have never been seen outside of Italy.
Dr Pinotti, who has a degree in politics and sociology from the University of Florence and is the founder of Italy’s National UFO Centre, is set to reveal more pictures and case files in his new book, UFO Contacts in Italy, next month.
Former director of investigations for the British UFO Research Association Philip Mantle, 59, who runs Flying Disk Press in Pontefract, West Yorks, said: “Photos of UFOs are still very rare but claims that these are photos of the inside of a UFO are quite unique.