A switch comprises voltage applying means for providing direct current potentials to first to third beams arranged with a spacing slightly distant one from another, and electrodes for inputting/outputting signals to/from the beams. By controlling the direct current potential provided to the beam, an electrostatic force is caused to thereby change the beam positions and change a capacitance between the beams. By causing an electrostatic force between the first and second beams and moving the both beams, the first and second beams can be electrically coupled together at high speed. Also, an electrostatic force is caused on the third beam arranged facing to the first and second beams, to previously place it close to the first and second beams. When the electrostatic force is released from between the first and second beams, the second beam moves toward the third beam thereby releasing the first and second beams of an electric coupling.