Rising house prices and a warm winter have encouraged more home owners to put their properties on the market.
Latest figures from the Real Estate Institute's website showed new listings rose to 9,857 in July, an increase of 9% compared to the previous month. The website accounts for about 95% of home listings.
The rise is failing to keep up with demand, however, particularly in Auckland and Christchurch where shortages have pushed up prices.
The website says the seasonally adjusted asking price in Auckland hit a record high of $639,685 in July. There was also a new high in Canterbury of $422,043.
Nationwide, the asking price was $465,191 - some $10,000 higher than the previous peak in May.
Realestate.co.nz marketing manager Paul McKenzie says despite the increase in new listings, the market remains tight, and he expects prices to continue rising.
He says if demand continues to outstrip supply prices will continue to go up and it's likely that at this time next year asking prices across the country will be higher again.