The Diamond Princess has been docked at the Yokohama port since Feb. 3 after it was determined some passengers had been sicked with the virus. Japan confirmed 66 new cases Monday and said officials may test everyone aboard the ship.
The American-based ship had completed a 14-day cruise in which it stopped in Hong Kong and several other Asian ports.
Japanese government officials and the cruise line were told by Hong Kong officials that an 80-year-old male passenger who departed the ship tested positive for the virus.
Coronavirus deaths worldwide have surpassed 1,100 and more than 45,000 have been sickened. The vast majority of those impacted are in mainland China, where the virus first began in the Hubei province in December.
The virus has killed more people than the Severe Acute Respiratory Syndrome (SARS) outbreak in China in 2003, when 774 people died and 8,000 were infected.
Thirteen cases have been confirmed in the United States.
The Associated Press contributed to this report.