New Zealand scored 89 out of 100 in non-government organisation Transparency International's Corruption Perceptions Index, narrowly beating Denmark to top spot.
The two nations tied for first last year.
Open Government Minister Clare Curran said she was pleased to see New Zealand's public service maintain its high standards.
But there was still plenty of work to be done.
``While we continue to hold the position of least-corrupt country and already have high standards of conduct and integrity, we must not be complacent.
``These results show we're not immune to behaviour and actions that can erode the great work done by the majority of people,'' Ms Curran said.
``Our focus must be on building and maintaining the public's trust in the integrity of the public sector.''
Ms Curran also said the Government would strive to further improve public transparency and free access to information.
The index, released yesterday, highlighted that most countries were making little or no progress towards ending corruption. Two-thirds of the 180 countries scored below 50.
New Zealand's Serious Fraud Office director, Julie Read, said a lack of public corruption would also help entice investment to New Zealand.
``The result indicates that people have a high degree of confidence in our public sector, and also supports our reputation as being a safe place to invest and do business,'' Ms Read said
