Akira Furusho, 40, was found collapsed and bleeding from the neck in a cage by a colleague on Monday after the Hirakawa Zoological Park closed for the day at 5 p.m., according to rescue workers.
Japanese police are investigating the death of a zookeeper who was apparently mauled by the white tiger at the animal park. He was confirmed dead after being taken to a hospital.
The Hirakawa Zoological Park opened for business on Tuesday, though the tiger enclosure was cordoned off.
The zoo was scheduled to remove the tiger from display to his sleeping chamber at the time.
The 375-pound animal is one of four rare white tigers at the city-operated zoo.
Caroline Wozniacki, Anastasija Sevastova set for China Open final
The 20th-ranked Latvian will face the victor of the semifinal between China's Wang Qiang and Caroline Wozniacki of Denmark.
Police said they are investigating whether proper safety measures were in place at the zoo.
White tigers are a genetic variant of the more common orange-and-black Bengal tiger but they have black stripes and white fur.
No one saw the moment of the apparent attack.
A veterinarian at the zoo used a tranquiliser dart to sedate the five-year-old male tiger, named Riku, before staff could reach Mr Furusho.
"We plan not to kill Riku and continue to keep it because the bereaved family asked us to do so", said Takuro Nagasako, a zoo official.