The Oscar-winning movie legend admits he toyed with the idea of stepping behind the camera for the film about the birth of Batman's nemesis, but eventually decided to step aside and let Todd Phillips take over.
"I know the film very well," Martin tells the BBC. "I know Todd very well. My producer, Emma Tillinger Koskoff, produced it. I thought about it a lot over the last four years and decided I did not have the time for it."
"It was personal reasons why I didn't get involved, but I know the script very well. It has a real energy and (in) Joaquin, you have remarkable work."
Scorsese also makes it clear he wasn't about to make a movie about a comic book character: "He (Joker) develops into an abstraction. It doesn't mean it's bad art, it's just not for me...," the revered filmmaker adds. "The superhero films, as I've said, are another art form. They are not easy to make. There's a lot of very talented people doing good work and a lot of young people really, really enjoy them."