Electric field-induced vibration of a freely suspended film (F.S.F) of smectic liquid crystal has been studied as a function of temperature, applied field and film thickness. By the application of sinusoidal electric field parallel to the film, not only a fundamental but also higher harmonics of the vibration has been observed. The fundamental and second harmonics components of the vibration strength has been proportional to the electric field and to the square of electric field, respectively. From temperature dependence, fundamental part of vibration increases steeply around the phase transition temperature from SmA to SmC^* phase. On the other hands, the second harmonic part shows the maximum strength just below the phase transition temperature. When FSF was in SmA phase, the optical response was smaller for the thick film, and the film vibration was smaller for the thin film in SmC^* phase.
