South Korea's main opposition Democratic Party's approval rating reached an all-time high this week, a poll showed Friday, apparently buoyed by the opposition-led impeachment of President Park Geun-hye last week.

According to pollster Gallup Korea, its support rating stood at 40 percent, up 5 percentage points from a week earlier, to reach the highest level since the party changed its name from the Democratic United Party in December 2015.

It marks the first time for a liberal party to garner a 40 percent approval rating since 1998 in Gallup Korea's polls.

The party outpolled rivals across the country, even in Daegu and North Gyeongsang Province, considered as conservatives' stronghold.

The ruling Saenuri Party posted 15 percent, up 2 percentage points on-week. It was followed by the splinter People's Party with 12 percent, down 1 percentage point.

Gallup Korea did not release the approval rating of the president as she was impeached last week. The poll was conducted on 1,004 people with a margin of error of plus or minus 3.1 percentage points. (Yonhap)