The country's 20th general election started at 6 a.m. (local time) at 13,837 polling stations nationwide, according to the National Election Commission, Xinhua news agency reported. The polling will end at 6 p.m.
The ruling Saenuri Party has fielded 248 candidates, with 268 candidates fielded by the main opposition Minju Party.
The minor People's Party and the Justice Party registered 172 candidates and 65 candidates each.
The ruling party aims to gain more than 150 seats, while the Minju Party has targeted more than 100 seats.
The People's Party and the Justice Party are aiming for 40 and 10 seats.