A MEMS switch includes a field generator which generates an electric field in a predetermined space, a beam located in the space and made of an electrically conductive material, the beam being flexed downward when subjected to an electrostatic force due to the electric field, the beam being deformed so as to return upward by an elastic restoring force upon extinction of the electrostatic force, a signal line electrically connected to the beam when the beam is flexed downward, and a protective cap covering the field generator, the beam, and the signal line, thereby sealing the field generator, the beam, and the signal line.