More than 2,400 people have been left homeless after Typhoon Megi lashed the southern shores of South Korea.
Megi was upgraded from a tropical storm as it passed over Japan
Five people are dead or missing after heavy rains and high-speed winds which forced the cancellation of dozens of domestic flights.
Typhoon Megi has already swept through Japan, leaving at least nine dead.
The storm is heading north-east and is expected to bring further heavy rain to northern Japan, which was hit by floods last month that killed 15 people.
Residents in Gwangju and other south-western towns were evacuated, as meteorologists reported winds of 130km/h (80mph) from Typhoon Megi, which means catfish in Korean.
The typhoon has now weakened, although is still powerful enough to bring heavy rain to the eastern regions as it moves across the country, weather officials said.
Some low-lying areas are already flooded, South Korea's Yonhap news agency reported.
Most of those killed by Typhoon Megi in Japan died in floods and mudslides, while two others were swept out to sea some 500km (310 miles) west of Tokyo.
Shikoku and the nearby Tsushima islands were particularly hard hit. Some 205mm (8in) of rain had fallen on some areas of Shikoku by 0900 (2400GMT) on Thursday.
Typhoons hit the region each summer, and last year's Typhoon Maemi, the strongest to hit South Korea in a century, killed at least 85 people.