Visa Information » New Zealand
If you are a citizen of one of the following countries which have visa waiver agreements with New Zealand, you do not need to apply for a Visitor Visa if you plan to visit New Zealand for 3 months or less: 

Andorra, Argentina, Austria, Bahrain, Belgium, Brazil, Brunei, Bulgaria, Canada, Chile, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hong Kong, Hungary, Iceland, Ireland, Israel, Italy, Japan, Korea (South), Kuwait, Latvia, Liechtenstein, Lithuania, Luxembourg, Malaysia, Malta, Mexico, Monaco, Netherlands, Norway, Oman, Poland, Portugal, Qatar, Romania, San Marino, Saudi Arabia, Singapore, Slovak Republic, Slovenia, South Africa, Spain, Sweden, Switzerland, Taiwan, United Arab Emirates, United States of America, Uruguay and Vatican. 

Australians can enter for as long as they like. 

New Zealand immigration 

New Zealand embassies