The won was quoted at 1,165.5 to the dollar at the conclusion of onshore trade, down 0.8 percent compared to Thursday's close of 1,156.0.
The currency gained 1.5 percent for the week, its biggest weekly gain since mid-March of this year.
South Korean shares also edged down due to a stronger dollar, with the Korea Composite Stock Price Index (KOSPI) closing down 0.3 percent at 2,017.63.
Offshore investors snapped a three-day buying session to sell a net 56.9 billion won ($48.85 million) worth of KOSPI shares on Friday.
The KOSPI was up 1.6 percent on the week, its third week of gains and the biggest weekly gain since mid-April.