An optical deflector and a light beam scanning apparatus characterized by stable amplitude and speed wherein the fluctuation of the resonant frequency resulting from various factors such as a temperature change is corrected to a predetermined level, and the amplitude of the resonant scanner is kept to a predetermined level. An electromechanical transducer is used as a control element to control the potential difference resulting from the electric charge occurring in the control element caused by rotational vibration of the optical deflector, whereby the fluctuation of the resonant frequency resulting from various factors such as a temperature change is corrected to a predetermined level and the amplitude of the resonant scanner is kept at a predetermined level. This arrangement provides an optical deflector and a light beam scanning apparatus characterized by stable amplitude and speed.