This brings the number of passengers to have died from the virus while on the cruise liner up to six.
Japanese news agencies made the announcement at around 1pm UK time.
The ship, which was quarantined off the coast of Japan, has recorded more than 600 coronavirus infections.
The Diamond Princess liner was carrying 3,700 people, including 78 Brits, when a male passenger disembarked at Hong Kong and trusted positive for the deadly disease.
On Sunday it was confirmed that four British people who arrived at a UK quarantine centre from the Japanese cruise ship had tested positive for coronavirus.
The Brit who has died is not one of these four people, Sky News reports.
Health Minister Jo Churchill has said she was aware a British man who had been on board the Diamond Princess cruise ship was “very poorly”.
She told BBC Radio 4’s World At One programme: “The Foreign Office are supporting the family of a British man who has been very poorly and was a passenger on board the Diamond Princess.
“I haven’t had confirmation, because obviously I’m on the telephone to you, but I was aware there was a gentleman who was very, very poorly, and I’m sure like me your thoughts and sympathies go out to his family at this time.”
More to follow.