Police said the latest victim died at an Auckland hospital on Sunday evening.
There were 47 people visiting the tourist destination of White Island when the volcano erupted on December 9, killing 13 people initially and leaving more than two dozen others in hospital with severe burns.
Two of the victims’ bodies have not been recovered after authorities believe they were washed out to sea in a storm soon after the eruption.
Helicopter pilots and boat operators helped the injured off the island immediately after the eruption, but emergency services did not return to the island to recover bodies until four days later because they considered the site remained too dangerous.
In a brief statement on Monday, police said they had been advised just before 11pm on Sunday of the latest death at Middlemore Hospital.
Police did not immediately the release the victim’s name.
Many of those killed and injured were Australian tourists who had been traveling aboard the Royal Caribbean cruise ship Ovation of the Seas.
White Island, also known by its Maori name, Whakaari, is the tip of an undersea volcano about 30 miles off New Zealand’s North Island and was a popular tourist destination before the eruption.
It is unclear if the privately owned island will ever be reopened for tourist visits.
Many people have questioned why tourists were still allowed on the island after New Zealand’s GeoNet seismic monitoring agency raised the volcano’s alert level on November 18 from one to two on a scale where five represents a major eruption, noting an increase in sulfur dioxide gas, which originates from magma.
New Zealand authorities are investigating the circumstances around the disaster.