Companies issued bonds worth 12.1 trillion won (10.8 billion U.S. dollars) in November, down 31.6 percent from the previous month, according to the Financial Supervisory Service (FSS).
It came as market rates went higher amid rising expectations for the Bank of Korea (BOK)'s interest rate hike.
The BOK raised its target rate by a quarter percentage point to 1.75 percent in late November, the first rate increase in 12 months.
Bonds, sold by industrial companies, declined 28.4 percent in the month, with issuance from financial firms sliding 25.4 percent. The asset-backed securities (ABS) sales plunged 69.1 percent.
The equity financing, including initial public offering (IPO) and rights issuance, reduced 10.9 percent over the month to 439.4 billion won (392.4 million U.S. dollars) in November.