A centrifugal fan includes an upstream side impeller, a downstream side impeller, a motor, and a housing arranged to accommodate the upstream side impeller, the downstream side impeller, and the motor. The housing includes a first intake port through which a gas is drawn from an outside, an exhaust port through which the gas is discharged to the outside, and a flow path defined within the housing to bring the first intake port and the exhaust port into communication with each other. The flow path includes a first wind tunnel portion positioned below the upstream side impeller to extend in a circumferential direction and arranged to receive a gas stream from the upstream side impeller and a second wind tunnel portion positioned above the downstream side impeller to extend in the circumferential direction and arranged to receive a gas stream from the downstream side impeller.