He is the first Briton to die of the disease, also known as Covid-19.
A spokesperson for the Foreign Office said: “We are supporting the family of a British man who has died in Japan and are in contact with local authorities.
“Our sympathies and thoughts are with his family at this difficult time.”
The Japanese Ministry of Health said the man was the sixth person from the ship to have died.
He was the first foreign passenger to die on the ship, the Kyodo news agency reported.
A spokeswoman for Princess Cruises, which operates the Diamond Princess, said: “All of us at Princess Cruises, including the crew of Diamond Princess, offer our sincere condolences to family members and friends for their loss.
“Our dedicated care team are on hand to provide support.”
In the UK, 19 people have been diagnosed with the disease.
On Friday, Wales reported its first patient to have tested positive for the virus and two more cases were identified in England.
The Welsh patient had recently returned from Italy, the site of Europe’s worst outbreak.
The two English cases had recently travelled from Iran, the Department for Health said, where the virus has rapidly spread, killing 22 amid 141 confirmed cases.
China has reported nearly 80,000 cases with almost 3,000 deaths. The virus has infected nearly 60 countries.
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