That brings the total number of cases to 61 on the Diamond Princess ship, which is quarantined in Yokohama harbour.
The Diamond Princess and another docked cruise ship, the World Dream, with thousands of passengers and crew members, remain under 14-day quarantines in Japan and Hong Kong.
Before Friday's 41 further confirmed cases, 20 passengers who were found to have the virus were escorted off the Diamond Princess.
About 3,700 people have been confined aboard the ship.
"It's going to be like a floating prison," British passenger David Abel wrote on Facebook.
He had set out on a 50th wedding anniversary luxury cruise on the Diamond Princess but found himself in his cabin, eating a "lettuce sandwich with some chicken inside".
More than 3,600 people on the other quarantined ship, the World Dream, underwent screening after eight passengers were diagnosed with the virus.
A third person has tested positive for coronavirus in the UK, the government confirmed on Thursday.
The number of people infected globally has risen to more than 31,000.