The typhoon, one of the most powerful to hit the country in several decades, hit Jeju Island (south) overnight before heading towards the port city of Busan, where large waves and strong rains damaged roads and seaside shops.
An elderly woman died Tuesday morning in floods that hit the eastern port city of Pohang, South Korean authorities said.
The death toll could rise later in the day, as authorities reported the disappearance of at least nine people on Tuesday afternoon.
Seven of them were in a flooded underground parking lot in Pohang.
More than 600 schools have been closed across the country as a precaution, and local airlines have canceled some 250 domestic flights.
Service was gradually resuming on Tuesday, however, as Hinnamnor headed for Japan.
In North Korea, leader Kim Jong-un oversaw a meeting to assess the country’s preparedness for natural disasters, state media reported on Tuesday.
Experts say North Korea is particularly vulnerable to flooding and heavy rains due to deforestation and the country’s poor irrigation system.
Tuesday morning, the typhoon was located above the Sea of Japan, 100 kilometers from the island of Tsushima (southwest).
More than 35,000 homes were without electricity in the Kyushu region (southwest), according to the local electricity supplier.
Hinnamnor is moving northeast at a speed of 45 km/h, with gusts of up to 180 km/h. It is expected to cause heavy rain in western Japan on Tuesday.
Several Shinkansen, Japan’s high-speed trains, were grounded due to strong winds and rain, and many local rail lines also halted service, operator JR Kyushu said.
At least 120 flights departing from and arriving at Kyushu airport have been canceled, state media NHK reported.