The 34-year-old's current deal expires at the end of this season, but reports have suggested that the veteran will be offered terms until 2016.
"It seems to me the president has already cleared what is the current situation, that's to say that between Juventus and Buffon there aren't problems for the negotiation," Marotta told Sky Italia.
"Buffon is Juventus and so he could stay at this club as long as he wants. So the contract could become a formality. We will have time to officially announce the deal in the next few weeks."
Buffon joined Juve from Parma in 2001.