Reports in Italy claim the Serie A club are keen to sign the Wales winger, who has caught the eye with some sparkling performances for Spurs this season - including a Champions League hat-trick at the San Siro against Inter Milan.
And Mancini reckons Juve would take a leap in quality if they were to prise the 21-year-old from the north London club.
He said in an interview to Turin sports newspaper Tuttosport: "Last year Bale had already proved his value but his career had not yet taken off.
"Now you would need a lot of money (to sign him). He is a very expensive player. Certainly, Juve with Bale would gain a lot.
"Moreover, what is certain is that if Tottenham decides to put him on the market, Bale would be the strongest target in the summer."