Seoul Mayor Oh Se-hoon, center, attends a hearing at the Seoul Central District Court in Seocho District, southern Seoul, Wednesday. He was sentenced to pay 10 million won ($6,760) for receiving opinion polls from political broker Myung Tae-kyun and having a sponsor cover the costs. Joint Press Corps

Seoul Mayor Oh Se-hoon was convicted Wednesday of violating the Political Funds Act and fined 10 million won ($6,760) over opinion polls conducted by political broker Myung Tae-kyun.

The sentence, if upheld on appeal, would strip Oh of his mayorship, dealing a critical blow to the political career of one of the nation's most prominent conservative heavyweights. The five-term mayor said he would appeal immediately.

The Seoul Central District Court found that Oh commissioned Myung to conduct five opinion polls ahead of the 2021 Seoul mayoral by-election and asked businessman and longtime supporter Kim Han-jung to cover 21 million won in polling costs.

“The defendant requested his supporter to pay the polling costs,” the court said in the ruling, adding that the payment constituted an illegal political contribution under the act.

“Having served as both a lawmaker and mayor, he had been well aware of the act, but he has kept denying his responsibility ... A sentence that would make him lose the public post is inevitable,” it said.

Under Korean law, elected officials lose their office when a fine of at least 1 million won or a prison sentence is confirmed. Oh said he would appeal, meaning the case will proceed to an appellate court and potentially the Supreme Court.

Oh had denied any wrongdoing throughout the trial, arguing that he never requested the payment and was unaware that Kim had covered the survey cost.

Prosecutors, however, argued that the payment was made at Oh’s request in exchange for polls conducted by Myung, who later emerged as a central figure in a series of political influence-peddling allegations.

The court sided with the prosecution on the key factual disputes, saying that Oh had requested five of the 10 opinion polls initially claimed by prosecutors, and asked Kim to pay for it. It said that the 21 million won transferred from Kim to Myung was intended to cover the polling costs.

Speaking to reporters after the ruling, Oh apologized for causing concern but rejected the court’s findings.

“Of the 10 published and unpublished opinion polls, the court today found five to be illegal. I cannot accept that. All of them should be found to be legal,” he said.

Oh argued that the conviction was based solely on Myung’s testimony and circumstantial evidence, without any direct proof.

Oh was indicted in December 2025 on charges of violating the act over allegations tied to the 2021 by-election.

Prosecutors said he received the results of 10 opinion polls conducted by Myung and had Kim cover 33 million won in polling costs.

Kang Cheol-won, who served as Oh’s campaign chief of staff and later as Seoul’s deputy mayor for political affairs, was indicted alongside him. Prosecutors alleged Kang communicated with Myung’s side, exchanged survey questions and helped coordinate the polling, while Kim made five payments linked to accounts linked to Myung's polling firm Future Korea Research Institute.

Prosecutors sought a prison term of one year and six months for Oh, along with forfeiture of 33 million won.

Prosecutors argued that Oh, Kang and Kim acted as part of a single arrangement in which polls were commissioned for Oh’s campaign and paid for by a third party, amounting to an illegal political contribution.

The ruling centered on two questions: whether Oh actually asked Myung to conduct the polls and whether he knew about or approved Kim’s payments.

According to prosecutors, Myung testified that Oh told him he needed a poll showing whether he could beat former lawmaker Na Kyung-won in the party primary and later directed him to work with Kang on the details.

Oh's side denied the allegations, saying Oh never commissioned any polls or asked Kim to pay for them. His lawyer said there was no record of direct contact, no clear record of discussions over survey design or sampling and no evidence showing that Oh reviewed the results or offered feedback.

They also argued that some surveys had already been prepared before the time Myung claimed Oh had requested them.

The ruling came after courts reached differing conclusions in other cases involving Myung.

Earlier this month, former President Yoon Suk Yeol was sentenced to two years in prison after a court found that Yoon and Myung had reached an implicit agreement over the repeated provision of free opinion polls ahead of the 2022 presidential election.

Prosecutors later cited that ruling in Oh’s case, arguing that the same reasoning should apply.

Former first lady Kim Keon Hee, however, was acquitted at both her first and second trials on the related charge. Those courts found that prosecutors had failed to prove she commissioned the surveys, with the appeals court saying Myung may have conducted and delivered them on his own initiative to expand his political influence.