Speculation the central bank could cut interest rates again to spur domestic demand also helped boost sentiment, analysts said.
In early August, the central bank unexpectedly cut its interest rate target by 25 basis points to a record low of 3.5 percent.
The benchmark Korea Composite Stock Price Index (KOSPI) closed 0.78 percent higher at 810.21 points, the highest close since June 1 when it ended at 815.77 points.
Korean Air, the country's largest carrier, rose 2.78 percent to end at 16,650 won and Asiana Airlines closed up 4.02 percent to 2,460 won as lower oil prices eased investors' concerns about a high fuel cost burden.
Among other decliners, top refiner SK Corp shed 1.2 percent to 45,250 won and smaller rival S-Oil ended down 1.17 percent at 50,700 won. Foreign investors bought a net 211.4 billion won on the main stock exchange.
Gainers led losers by 423 to 280, with 106 shares ending unchanged. Trading volume reached 284.9 million shares worth 1.8 trillion won, versus 262 million shares worth 1.62 trillion won on Wednesday.
The junior Kosdaq rose 0.69 percent to end at 358.79.
The September KOSPI 200 futures index gained 0.35 points to 103.15, while the underlying KOSPI 200 spot index added 0.38 points to 103.25.