The figures came from a Freedom of Information request by the Scottish Conservatives. The average wait for a property in Argyll and Bute is 313 days.
Mr Cameron said: “While the increase is relatively modest compared to other areas in Scotland I am nevertheless concerned that the trend here in Argyll and Bute is up. That is bad news for vulnerable people in our area who require a property. We need to see action to reverse the trend.
“Argyll and Bute Council has had to make massive savings in recent years and this is bound to have an impact on its ability to deliver services.”