The 31-year-old man was surfing at a beach north of Sydney in New South Wales state when he was attacked by the shark, ambulance service spokesman John Wilson said.
Fishermen took the man to an ambulance station, and he was later flown by helicopter to a hospital in Newcastle, 125 kilometers (78 miles) north of Sydney, the AP reports.
The injury was not life threatening, he added.
Many species of sharks are common in Australian waters, and attacks are sometimes reported when sharks venture close to popular beaches. It was unclear what kind of shark attacked the man.