A rectifying device includes an air flow generator. The air flow generator is disposed at an exterior member of a vehicle. The exterior member is adjacent to a detector of a sensor that is disposed such that at least a portion of a detection range of the detector includes a rear region behind a plane in a traveling direction of the vehicle. The plane is parallel to a width direction and a vertical direction of the vehicle. The air flow generator is configured to generate an air flow that separates, from the detector of the sensor, travelling wind that accompanies travel of the vehicle. The air flow generator includes a plasma actuator that includes at least a pair of electrodes and a power source that is configured to apply an alternating current voltage to the electrodes.