The actor has defended his friend and collaborator's casting as the caped crusader as he thinks the role is easier than some of the characters he has portrayed in recent times, such as undercover CIA agent Tony Mendez in his Oscar winning film 'Argo'.
Damon told The Times of India newspaper: ''You know, he's not playing [Shakespeare's] King Lear. It's Batman! Certainly within his skill set. If anybody saw 'Argo' or 'The Town', and all the work he's been doing lately, it's way more nuanced and interesting and way more difficult than Batman.
''Batman just sits there with his cowl over his head and whispers in a kinda gruff voice at people.''
Damon, 42, added playing Batman's alter ego, reclusive businessman Bruce Wayne, is the more challenging part of the role, but said: ''Ben will be great at that.''
While the duo have teamed up for many previous projects, Damon has ruled out appearing as Batman's sidekick, Robin.
He said: ''I am a little older than Ben. I never saw Robin as older than Batman. Somebody sent me a picture actually [of me as Robin], it was really funny. But it's safe to say I won't be Robin.''
Affleck's first appearance as Batman will be in the sequel to 'Man of Steel' - rumoured to be called 'Batman Vs Superman' - appearing alongside Henry Cavill as Superman.