The police are investigating the details surrounding the death of the official, Yasushi Moriya, 52, viewing it as apparent suicide, the television network said.
The Tokyo 2020 Olympic Games were postponed last year due to the coronavirus pandemic. Government and organizing officials have consistently said the Games would go ahead despite a recent rise in Japan's coronavirus numbers.
"We do not speculate," an International Olympic Committee spokesperson said in April. "We are fully concentrated and committed to the successful delivery of the Olympic Games Tokyo 2020 this year, and working at full speed towards the opening ceremony on July 23."