It is the first positive test at Oakwell in five rounds of testing. The Reds restarted full contact training on Wednesday with the season set to resume on June 20.
Training will continue as usual this week.
A club statement said: “ Barnsley FC can confirm that one person has tested positive for the COVID-19 virus following a round of testing on Friday 5 June.The single positive test is from an asymptomatic member of backroom staff who had tested negative in all four previous rounds.
“The individual will now follow the relevant guidance and undergo a period of isolation whilst remaining in close communication with club personnel, before being re-tested at a later date.Many have worked tirelessly to ensure that Oakwell remains a safe environment for players and staff alike. Barnsley FC will continue to follow EFL protocol and instruction.The staff member is safe and upbeat. No further comment will be made.“