The benchmark Korea Composite Stock Price Index rose 5.52 points, or 0.23 percent, to 2,371.92 in the first 15 minutes of trading.
Analysts expected the Seoul stock market to move in a tight range this week ahead of the US Federal Reserve's annual economic policy symposium in Jackson Hole, Wyoming.
Large-cap stocks traded mixed across the board, with leading steelmaker POSCO rising 0.91 percent and top chemical firm LG Chem Ltd. gaining 1.50 percent.
But market bellwether Samsung Electronics Co. fell 0.21 percent and top carmaker Hyundai Motor Co. shed 0.68 percent.
The local currency was trading at 1,127.40 won against the US dollar, up 4.40 won from the previous session's close. (Yonhap)