An electronic device is provided, including a conductive substrate, an electret diaphragm, a plurality of spacers, a first electrode, and two second electrodes. The conductive substrate has a plurality of openings. The spacers are disposed between the conductive substrate and the electret diaphragm to define an acoustic projecting portion and two acoustic receiving portions on the electret diaphragm. The first electrode is disposed on the acoustic projecting portion and coupled with the conductive substrate for generating an acoustic signal. The second electrodes are disposed on the acoustic receiving portions and coupled with the conductive substrate, wherein the acoustic receiving portions receive the acoustic signal and vibrate to vary an electrical field between the second electrodes and the conductive substrate.