Moon's job approval rating came to 49.4 percent in a weekly survey conducted by Realmeter.
The reading marks a 1.6 percentage-point drop from a week earlier. The latest survey was conducted Monday through Thursday, involving 2,011 adults across the nation.
The drop coincided with the second U.S.-North Korea summit held in Hanoi last week, but the local pollster noted the outcome of the Hanoi meeting may have had little or no effect on its latest survey as the meeting ended shortly before the survey was concluded.
The meeting between U.S. President Donald Trump and North Korean leader Kim Jong-un fell through after both leaders walked from their second bilateral summit with no agreement.
The pollster partly attributed the drop in Moon's job approval rating to the national convention of the main opposition Liberty Korea Party (LKP) to elect its new leadership that may have helped turn the public's attention to more conservative views.
The ruling party's approval rating plunged 2.1 percentage points on-week to 38.3 percent.
The LKP's rating gained 2 percent to 28.8 percent, narrowing its gap with that of the ruling party to a single-digit figure. The gap once stood at nearly 40 percentage points when the Moon Jae-in administration took office in May 2017.
The approval rating of the minor opposition Bareunmirae Party gained 0.7 percentage point to 7.3 percent, while that of the progressive Justice Party slipped 0.2 point to 6.9 percent.
The approval rating of the Party for Democracy and Peace dropped 0.5 point to 2.7 percent. (Yonhap)