Average monthly rents across the country rose to a new record level during the second quarter of the year.
According to the latest quarterly Rental Report by Daft.ie, on average the cost of renting is now €1,391 per month.
The increase marks the 13th consecutive quarter of record rents.
However, the 6.7% rise over the same quarter last year is the lowest rate of rental inflation recorded since the last three months of 2013.
Nonetheless, the average listed rent per month is €361 higher than the last peak 11 years ago.
Ronan Lyons, economist at Trinity College Dublin and author of the report, said the moderation in increases was more likely due to limits on affordability, rather than improvements in the supply of rental properties.
"Availability on the rental market remains at levels that were unprecedented prior to 2015," he said in a statement.
"For example, in the Dublin market, there were just 1,541 properties available to rent on August 1st. While that's up from 1,121 two years ago, it's well below the average of 4,700 for the preceding decade."
According to Daft, the slowdown has been principally driven by the capital, although other main cities have also seen inflation rates moderate too.
In Dublin, rent growth in the last quarter was 4.5% compared to a year earlier, bringing average rents to €2,023 a month.
That compares to an annual inflation high of 13.4% in mid-2018.
While in Cork they were up 7.9% year on year to a monthly average of €1,366.
Limerick rents climbed 10.5% over the past 12 months to €1,225 a month, just ahead of the average increase in Waterford of 10%, bringing average rents each month there to €1,013.
The highest rent inflation was recorded in Galway, where rents during the last quarter were 15.5% higher compared to the same period a year earlier.
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Mr Lyons said the construction of up to 25,000 new rental units in the next few years would certainly help moderate the situation further.
However, he said that not only do policymakers need to target the inflation, but they also need to bring rents down to an affordable level.
Commenting on the report, the Irish Property Owners' Association said the report shows the availability of rental property is disturbingly low.
"The private rental market is shrinking rather than expanding, Rent Pressure Zones are a blunt instrument and do not take into account the level of rent being charged or the indebtedness of a landlord, making it uneconomical for some landlords to continue renting property," said Stephen Faughnan IPOA Chairman.
"The State needs to protect the existing supply of accommodation as well as incentivise further investment in the sector."
Minister for Housing, Planning and Local Government, Eoghan Murphy, said rent pressures and the insecurity this is causing for people is very much a priority for the government because rents are still too high.
"It's worth pointing out that the period covered in this report was before the significant changes introduced in the Rent Reform Bill earlier this year and passed in June," he said.
"These reforms strengthen rent pressure zones considerably, remove a number of opt-outs, and give new legal powers and resources to the RTB to enforce rent controls."
"Separately to this we are seeing a continued increase in purpose built student accommodation, which is positive for students, but also in terms of freeing up houses and apartments in other parts of the rental sector."