Exemplary embodiments of the invention provide a micromechanical electrostatic resonator which designs high frequency, increases a ratio of output voltage to input voltage, and designs low drive voltage or reduced power consumption. A micromechanical electrostatic resonator of exemplary embodiments includes a plate-shaped vibration body, a pair of electrodes arranged oppositely to each other at both sides of the vibration body with a gap from an outer circumferential portion of the vibration body, a feeding device to apply in-phase alternating-current power to the pair of electrodes, and a detecting device to obtain an output corresponding to a change in capacitance between the vibration body and the electrodes. The planar shape of the vibration body takes a shape having a curved outline which comprises a neck portion.