The Ugandan Olympic team is currently in the Japanese city of Izumisano.
On Friday afternoon (local time), however, 20-year-old Julius Ssekitoleko was reported missing.
A search operation for the weightlifter has now been initiated by the police, reports Reuters.
Yahoo Japan and the TV channel NHK write that Ssekitoleko's disappearance should have been noticed in connection with the daily PCR test, as he should not have been in the hotel room.
The Olympics will be inaugurated in a week and will end on August 8.