Export, which accounts for about half of the economy, amounted to 26.8 billion U.S. dollars in the Oct. 1-20 period, down 19.5 percent from a year earlier, according to Korea Customs Service.
The number of working days reduced by one day in the cited period. The daily average export slipped 13.5 percent in the period.
Import contracted 20.1 percent to 25.4 billion dollars, sending the trade surplus to 1.4 billion dollars.
The outbound shipment continued to fall for 10 straight months through September amid the global trade dispute and the global chip industry's downturn.
Chip export tumbled 28.8 percent in the 20-day period, with those for oil products, automobiles and ships skidding 38.4 percent, 6.5 percent and 8.4 percent each.
Shipment of telecommunications devices, such as smartphone, jumped 44.8 percent, with home appliances export growing 11.7 percent in the period.
Export to China, South Korea's biggest trading partner, diminished 20 percent, with those to the United States and the European Union (EU) plunging 17.4 percent and 36.6 percent respectively.
Shipment to Japan dived 21.3 percent in the 20-day period, after falling 6.6 percent in July, 13.1 percent in August, and 13.5 percent in September.
Import from Japan also plunged 30.1 percent in the 20-day period, after tumbling 16.6 percent last month.
It came amid the ongoing trade spat between Seoul and Tokyo. Japan tightened control in July over its export to South Korea of three materials vital to produce memory chips and display panels, the mainstay of the South Korean export.
In August, Japan dropped South Korea off its whitelist of trusted trading partners that are given preferential export treatment. In response, Seoul removed Tokyo from its whitelist of trusted export partners.