There is provided a mechanical motion switch whose structure is simple, which is a microminiature, which can be used for a long time even in a such a severe environment as a high temperature state, and whose reliability is high. A ceramic-made pedestal of an approximately rectangular shape is fixed to a board and, in the pedestal, there is formed a reverse L-letter shape groove continuous with a base end face and an upside face. A high elasticity wire having an electrical conductivity is fitted and fixed to the groove while being bent, and has a lead penetrating through the board and an arm part extended in a direction horizontal to the board, and a tip part of the arm part is made an action end. In the action end, there is formed, in a position separated from the board, a metal-made deadweight movable by a swing by an elasticity of the arm part. On the board just below the deadweight, there is provided a contact having the electrical conductivity, which is support-fixed to the board by a lead. And, the pedestal, the arm part, the deadweight and the contact are covered by a case.