A MEMS resonator includes a beam oscillator that oscillates mechanically when an electrostatic force is applied. A supporter oscillates along with the oscillator and supports the oscillator; and at least one electrode includes an opposing face to the oscillator across a gap, wherein an electric current generated by the oscillation of the oscillator is output through an output terminal connected with the oscillator or electrode. The oscillator oscillates in a torsional resonance mode with a center being a longitudinal axis of the oscillator, and opposing faces of the oscillator and the electrode are made of semiconductors of which the conductive types are different from each other. Additionally, a surface part of the oscillator including the opposing face is doped with an impurity at a higher density than other part of the oscillator.