Abstract: A rotor blade is provided with rotary spoilers rotatably supported in recesses formed in a blade body, respectively, so that the upper surface of each rotary spoiler serves as a portion of the wind surface of the rotor blade. Each rotary spoiler is turned so as to protrude from the wing surface of the blade body to make the rotary spoiler exercise its function when the rotor blade is turned to an appropriate rotary angular position to control noise and vibrations by changing the lift of the rotor blade. Each rotary spoiler is driven for turning by a driving mechanism having a driving member made of a piezoelectric material, and the operation of the driving mechanism is controlled by a controller.