Tokyo organizers issued a statement Wednesday saying it was a male employee in his 30s who worked at the headquarters building in a part of Tokyo known as Harumi.
Organizers said he was in quarantine at home and gave no further details.
The Tokyo Olympics were postponed last month until 2021 because of the coronavirus pandemic.
The committee employs about 3,500 people, and organizers say about 90% have been working from home for the last several weeks.
Organizers said the area in which he worked would be disinfected, and people who worked nearby have been told to stay home.
The Olympics are scheduled to open on July 23, 2021, but questions persist if that will be possible in light of the pandemic. (AP) ATAT