To provide an electromechanical signal selection device which can be
miniaturized and highly integrated and which can selectively output only
a signal of a predetermined frequency without providing any sensitive
vibration sensing mechanism, and electric equipment using the
electromechanical signal selection device.A micro-vibrator serving as a
resonator is provided. The micro-vibrator can be excited by an external
force to excite vibration of the micro-vibrator. A material whose
physical property is changed in accordance with a structural change is
used as the micro-vibrator. Thus, a sensitive electromechanical signal
selection device is obtained.