He had been hospitalized for five days since January 10 and was released on Wednesday as the symptoms relieved.
Scientists are baffled by the virus which has never been seen before.
Japan confirmed its first "Chinese pneumonia" case on Thursday.
The World Health Organization (WHO) had previously warned that the new virus could spread and alerted hospitals around the world. With all this happening inside the Chinese borders, unexpected cases broke out outside China too.
The market has been closed since 1 January.
A vendor gives out copies of newspaper with a headlines of "Wuhan break out a new type of coronavirus, Hong Kong prevent SARS repeat" at a street in Hong Kong, Saturday, Jan. 11, 2020. "The traveler is a 61-year-old woman and is recovering", said the Thailand health officials.
The Chinese woman was quarantined after arriving in Bangkok from Wuhan, in eastern China, where the outbreak began in December. She is now in a stable condition.
She said the organisation was preparing for the possibility of a wider outbreak. The city is home to 11million people. Some of the virus types cause less serious disease, while some - like the one that causes Middle East Respiratory Syndrome (MERS) - are far more severe.
Early evidence has linked the virus to a seafood market in Wuhan, where several infected patients worked and were in direct contact with animals.
The wife said she has not had some exposure to the marketplace.
Later that evening, Japan's National Institute of Infectious Diseases, which had prepared diagnostic kits after China shared the genetic sequence of the coronavirus on Sunday, confirmed that the man had been infected with the new coronavirus strain.
With Chinese New Year approaching on January 25, when many Chinese tourists visit Thailand, the World Health Organization called on Thai authorities, the public and holidaymakers to be on alert. One suspected case was also reported in Singapore.
SARS originated in China in 2002 and infected more than 8,000 people across 37 countries.