The by-election for the chief of Seoul's Gangseo District kicked off Wednesday.
According to the National Election Commission, ballots will be taken at about 130 polling stations within the district between 6 a.m. and 8 p.m. Wednesday.
Eligible voters in the district can cast their ballots with government-issued photo identification.
The by-election comes after former district chief Kim Tae-woo was removed from office in May upon receiving a suspended prison sentence for leaking official secrets he had obtained while working for a special inspection team under the former Moon Jae-in administration.
The six-way race includes Kim as the candidate for the ruling People Power Party, having regained his right to run with a presidential pardon in August, while the main opposition Democratic Party is fielding former National Police Agency deputy chief Jin Kyo-hoon.
The two-day early voting for the election ended with a record turnout of 22-point-64 percent last Saturday, the highest ever figure for any of the country's by-elections and local elections.