A MEMS device with a first electrode, a second electrode and a third electrode is disclosed. These electrodes are disposed on a substrate in such a manner that (1) a pointing direction of the first electrode is in parallel with a normal direction of the substrate, (2) a pointing direction of the third electrode is perpendicular to the pointing direction of the first electrode, (3) the second electrode includes a sensing portion and a stationary portion, (4) the first electrode and the sensing portion are configured to define a sensing capacitor, and (5) the third electrode and the stationary portion are configured to define a reference capacitor. This arrangement facilitates the MEMS device such as a differential pressure sensor, differential barometer, differential microphone and decoupling capacitor to be miniaturized.