The recent surge in COVID-19 cases caused business sentiment among South Korean companies to fall for the first time in five months in September.
Data from the Bank of Korea show that the Business Sentiment Index for all industries stood at 64, down two points from the previous month.
A reading below 100 indicates that pessimists outnumber optimists.
By sector, sentiment among non-manufacturing businesses fell four points on-month to 62, the most pessimistic being leasing services and wholesale and retail industries.
But sentiment among manufacturers edged up two points to 68 mostly thanks to a pick-up in the price of steel products.