The negative assessment on Moon's conduct of state affairs shrank 1.6 percentage points to 55.1 per cent, according to the Realmeter survey.
Support for Moon's ruling Democratic Party added 0.6 percentage points to 31.9 per cent last week, reports Xinhua news agency.
The main conservative opposition People Power Party won 38.4 per cent of support last week, down 0.6 percentage points from the previous week.
The minor centre-right People's Party garnered an 8.7 per cent of approval score, trailed by the minor centre-left Open Democratic Party with 4.9 per cent and the minor progressive Justice Party with 3.8 per cent.
As for the approval rating of presidential candidates, support for the Democratic Party's Lee Jae-myung gained 0.1 percentage points over the week to 36.8 per ent last week.
Support for the People Power Party's Yoon Suk-yeol increased 1.4 percentage points to 42 per cent last week.
The country's presidential election is scheduled for March 9.