Should we need a visa to China?

We are 2 Australian Passport holders travelling to Japan to board a cruise ship to cruise around Japan and have a 2 day stop over in Shanghai. We have bought 2 different tours with the cruise ships for 2 days in Shanghai. We are wondering whether we need any visa to China to go ashore in Shanghai. After Shanghai the ship will travel back to Japan then South Korea and back to Japan again.
Any advice will help. Thanks.