In addition, Jewel Changi Airport, the entertainment and retail complex inside the CAG, will also be closed for 14 days, Xinhua news agency quoted the announcement as saying on Wednesday.
CAG said that Changi Airport remains open for air travel during this period.
Passengers may also continue to be dropped off and picked up from the airport.
Access to the passenger terminal buildings will be restricted to only passengers with air tickets and essential airport workers.
Some essential services and the food and beverage outlets will remain open.
CAG said that all workers in Changi Airport's Terminals 1 and 3, and Jewel Changi Airport, have been undergoing mandatory Covid-19 tests in a special testing operation starting May 9, following the detection of cases at the airport.
This is to quickly detect, isolate and treat any potential positive cases in the airport community, it added.