The survey of more than 500 leading valuers and surveyors found that 90 per cent of investment properties are being sold to buyers who plan to use them as their primary residence.
Four in five (79 per cent) surveyors also found that the number of owners planning to buy a new investment property had fallen in the last 12 months.
With more landlords selling off their stock as a result of a stricter regulatory environment, it's no surprise that supply has been problematic.
One of the changes that has had the biggest impact has been the abolition of mortgage income tax relief, which has been replaced by a 25 per cent tax credit.
Some 44 per cent of surveyors believe that the decline in rental stock over the last year has pushed up house prices.
In fact, 45 per cent of London surveyors reported an increase in above asking rental prices.
Rob Owens, head of research at e.surv, said: "The buy-to-let market is currently facing a number of challenges, with rising mortgage rates at the forefront of landlords' concerns."
"The government must take steps to support the buy-to-let market and ensure it remains a viable investment option for landlords."