The number of transactions rose by about 6 per cent to some 6,600.
HDB's Resale Price Index rose to 180.3 points in the second quarter from 174.8 points a quarter ago.
Analysts believe this is due to a supply crunch of resale flats. They said this is partly brought on by policy measures to cool down the private property sector.
An example is the lower 60 per cent Loan-To-Value limit on housing loans for individuals with existing housing loans at the time of the new housing purchase.