The virus first appeared in the central Chinese city of Wuhan, and has infected more than 20,000 people, killing 425 and spreading to more than two dozen countries.
The latest confirmed case brought South Korea’s total number of patients to 16.
She is a 42-year-old Korean woman who returned to the country from Thailand on January 19, according to Seoul’s health authorities.
She started showing symptoms six days later, and was diagnosed with the virus today, they added.
But the Korea Centers for Disease Control and Prevention said it was too early to conclude whether the patient contracted the virus while in Thailand, where 19 cases have been confirmed so far.
“We need detailed research through an epidemiological survey,” Jeong Eun-kyeong, director of KCDC, told reporters.
South Korea has so far seen at least four cases of human-to-human transmission of the virus, while a hospitalised Chinese tour guide is believed to have caught the illness while working in Japan.
A South Korean ban came into force today blocking entry to foreigners who have visited China’s Hubei province in the previous 14 days.