The reading, a de facto approval rating, marked a slight increase from 87 percent a week earlier.

The survey was conducted on 1,003 adults throughout the country. It had a margin of error of plus or minus 3.1 percent, with a confidence level of 95 percent.

Those expecting Moon to do a poor job as the top elected official came to 6 percent, down 1 percentage point from a week earlier, according to the local pollster.

Moon's approval rating also compared with the 70 percent for his ousted predecessor Park Geun-hye in her third week in office, it noted.

President Moon came into office on May 10, one day after a rare presidential by-election caused by the March 10 ouster of Park over corruption allegations.

In the latest survey, Moon's ruling Democratic Party secured an approval rating of 51 percent, becoming the first liberal party ever to breach the 50 percent mark in the country's history.

The approval rating of the main opposition Liberty Korea Party remained unchanged over the cited period at 8 percent. (Yonhap)