A gas supply system includes a loading/unloading stage including a cradle loader where a cradle loaded with a gas container is loaded, a test buffer chamber is configured to test the gas container, and a loading/unloading robot configured to transfer the gas container between the cradle and the test buffer chamber. A gas supply stage includes a storage queue configured to temporarily store the gas container, a gas supply cabinet where the gas container is mounted, and a transfer robot configured to transfer the gas container between the test buffer chamber and the storage queue and between the storage queue and the gas supply cabinet.