A member of staff at the Tokyo 2020 Organising Committee has tested positive for coronavirus, representing the organisation's fourth recorded case so far.
The employee in question is male, in their 30s and employed at a Harumi office, Tokyo 2020 said.
Two other positive tests from the Harumi office were reported in August, while the first known case came to light in April.
"The affected employee has been working from home from 7 July onward; his last day working on site was on 6 July", Tokyo 2020 said.
"Tokyo 2020 will continue to work with relevant organisations to prevent the spread of COVID-19 and take all necessary measures to maintain a safe and secure working environment for our staff."
Japan reported 669 new COVID-19 cases yesterday.
After a spike in late July and early August, the nation has not reported more than 1,000 new cases in a day since August 23.
Capital Tokyo has been the epicentre of Japan's coronavirus outbreak.
The Tokyo 2020 Organising Committee is made up of approximately 3,800 workers from organisations including the Japanese Olympic Committee, Japanese Paralympic Committee, Tokyo Metropolitan Government and Japanese Government.
Some staff began returning to offices in June, with coronavirus countermeasures put in place.
In March, the global health crisis lead to the Tokyo 2020 Olympic and Paralympic Games being postponed until 2021.
A panel assessing coronavirus countermeasures at the postponed Games met for the first time yesterday.
Tokyo 2020 chief executive Toshirō Mutō was among the attendees, with the Japanese Government, Tokyo Metropolitan Government and Tokyo 2020 Organising Committee forming the three-party council.
Kazuhiro Sugita, Japan’s deputy chief cabinet secretary, has been tasked with leading the discussions.
The Olympic Flame went on public display at the Japan Olympic Museum earlier this week and a full Torch Relay is planned in 2021.