A landside engulfed houses and flooding swept away vehicles in the resort town of Gapyeong, northeast of capital Seoul, on Sunday.
A landslide hit a campsite in the town, leaving a man in his 40s dead, two family members missing, and 24 other people stranded, according to the local fire service.
One person was killed after their house collapsed and another was found dead after being swept away by a swollen stream, while six people remain missing in the town and the southern city of Gwangju.
The Interior and Safety Ministry said eight people were killed and six others reported missing in the southern town of Sancheong on Saturday after heavy downpours caused landslides, house collapses and flash floods.
Earlier in the week, three people were found dead in a submerged car, and a person was also killed when their car was buried by soil and concrete after a retaining wall of an overpass collapsed in Osan, just south of Seoul.
Southern regions have been hit by up to about 600-800mm (24-31 inches) of rain since the downpours began n Wednesday.
About 3,840 people remained evacuated from their homes by Sunday morning.
The heavy rainfall moved north overnight and alerts have been lifted throughout the country, ministry officials said.
