An electric energy generating device. The electric energy generating device includes a piezoelectric structure including a material having piezoelectric characteristics, and an insulating film including a material having electret characteristics. When external energy is supplied to the insulating film, the insulating film contacts the piezoelectric structure and the piezoelectric structure is then deformed to generate electric energy. Also, electric energy is generated when an electrostatic capacitance between the insulating film and a substrate adjacent to the insulating film changes.