The Labour-backing physicist said he would vote for Mr Corbyn and that he approves of many of his policies but he believes he should quit "for the sake of the party".
The Cambridge University academic told The Times: "I regard Corbyn as a disaster.
"His heart is in the right place and many of his policies are sound but he has allowed himself to be portrayed as a left-wing extremist.
"I think he should step down for the sake of the party."
Professor Hawking's comments came as shadow chancellor John McDonnell tried to heal divisions within the party amid claims that a "soft coup" was under way.