To perform realizable controlled wind speed fluctuation at a blowout hole of wind tunnel equipment so as to simulate a natural wind for a test of an aerodynamic noise of an automobile or the like caused by a fluctuating wind.

The air is forcibly circulated by a fan 2 through an approximately circularly-continuous air blowing passage 3 and blown out to a measuring part 5 through the blowout hole 4. This device is equipped with a high-pressure air storage tank 11A for blowing forcibly the air into the flow of the main stream air in the air blowing passage 3 and increasing the flow rate of the air blown out to the measuring part 5 through the blowout hole 4 to thereby heighten the wind speed, and a vacuum tank 11B for sucking forcibly the air from the air in the air blowing passage 3 and decreasing the flow rate of the air blown out to the measuring part 5 through the blowout hole 4 to thereby lower the wind speed.