The negative assessment on Moon's conduct of state affairs fell 0.1 percentage point to 54.4 per cent, according to the Realmeter survey.
Support for Moon's ruling Democratic Party lost 0.1 percentage to 32.6 per cent last week, Xinhua news agency reported.
The main conservative opposition People Power Party garnered 37.1 per cent of support last week, up 1.8 percentage points from the previous week.
The minor centre-right People's Party won a 7.4 per cent of approval score, followed by the minor centre-left Open Democratic Party with 6.9 per cent and the minor progressive Justice Party with 3.5 per cent.
The result was based on a survey of 2,520 voters conducted from September 6 to 10.
It had plus and minus 2.0 percentage points in margin of error with a 95 per cent confidence level.