A circulating EFEM includes an introduction port for introducing a gas, a housing for circulating the introduced gas, and a discharge port for discharging the gas from the housing into a discharge pipe. The discharge port includes a box and a damper. The box is disposed to surround a discharge opening formed on the housing and connected to the discharge pipe. The damper is disposed inside the box to close and open the discharge port and adjusts a discharge amount of the gas via the discharge opening by at least partially moving in response to a differential pressure between the housing and the box.