Whanganui is one of six regions that experienced double digit growth in rent increases in the past year.
That's according to the latest Trade Me Property Rental Index which says the median rental in Whanganui has increased 12 per cent to $320 per week.
The national median rent is up 3.4 per cent on last year to a record-breaking $460 per week.
The index is produced from Trade Me Property data of properties that have been rented in the month by property managers and private landlords.
Head of Trade Me Property Nigel Jeffries said the increases have been driven by a lack of available rentals.
"Supply simply cannot keep up with the demand we are seeing and it's rare for rental properties to be coming on and off the market so quickly," Mr Jeffries said.
"We're seeing rentals are being listed for a very short time as fierce demand means landlords can have their houses listed and then tenanted in record time.
"While we did see rent rises around this time last year, the market is much tighter this year and the coming months are not looking good for flat-hunting Kiwis."
However, Landlords Link managing director Tracey Onishenko says her property management company's challenge is finding suitable tenants rather than a lack of rental properties in Whanganui.
"There's a lot of talk about the lack of properties but we've never had that problem," Mrs Onishenko said.
"We have about 15 properties available at the moment at a variety of prices.
"We are finding it quite difficult to find suitable tenants and there don't seem to be as many people around looking. It's quite slow for this time of year. A lot of people we see have bad credit and landlords these days aren't going to give those people a second chance."
Mrs Onishenko said 40 people might attend a rental property open home but only one or two of those would be suitable once credit and reference checks had been done. There were also insurance difficulties for landlords if tenants had a poor credit or tenancy history.
"Previously landlords could give tenants a three-month trial so they could give them a chance but the law has now changed."
The rental market has also changed because many people are using Kiwisaver to buy their own homes rather than being long-term renters, Mrs Onishenko said.
Many of the people seeking rental properties were moving to Whanganui from larger cities, mainly Wellington, Palmerston North and Auckland.
"Some are only coming for one or two years so they don't want to buy. A lot of people can work from home and they are renting some amazing houses.
"We also get lots of calls from investors, including Australian investors and Auckland investors. The investors are buying better quality properties than they used to and rentals of $300 to $350 are about average."