Turnout for Wednesday's presidential election stood at 57.6 percent as of 5 p.m., just one
hour before polls were scheduled to close, the election watchdog said.
The rate is far below the 64.5 percent recorded at the same time during the 2002 presidential election.
Of 37,653,518 eligible voters across the country, 21,677,712 voted.
The National Election Commission is concerned that South Korea is heading for a record-low voter turnout of barely over 60 percent.
North Gyeongsang Province had the highest voter turnout of 63.8 percent, followed by 62.3 percent in North Jeolla Province, 61.4 percent in the city of Daegu, 60.3 percent in South Jeolla Province and 58.5 percent in the city of Ulsan.
Incheon, a city west of Seoul, had the lowest turnout with 54.8 percent.
Voter turnout in South Korea has been on a downward trend since the direct popular vote was restored in 1987, following seven years of authoritarian rule by the Chun Doo-hwan regime.
The 1987 election saw a turnout of 89 percent in a pro-democracy atmosphere, but dropped to 81 percent in 1997 and 71 percent in 2002.
Polls will remain open until 6 p.m. Wednesday and the election watchdog expects the leading candidate to emerge around 9 p.m.