Power generator

A power generator comprising:

• a magnetostrictive rod through which lines of magnetic force pass in an axial direction thereof, the magnetostrictive rod formed of a magnetostrictive material;
• a coil arranged so that the lines of magnetic force pass inside the coil in an axial direction of the coil whereby a voltage is generated in the coil due to variation of density of the lines of magnetic force;
• and
• a bias stress generating mechanism for generating compressive stress in the magnetostrictive rod in a natural state,
• wherein the magnetostrictive rod has one end portion and the other end portion, and
• wherein the power generator is configured to generate the voltage in the coil due to the variation of the density of the lines of magnetic force when the other end portion of the magnetostrictive rod is displaced with respect to the one end portion of the magnetostrictive rod in a direction substantially perpendicular to the axial direction of the magnetostrictive rod to expand and contract the magnetostrictive rod, wherein the bias stress generating mechanism includes a beam member which is arranged along the magnetostrictive rod and allows the one end portion and the other end portion of the magnetostrictive rod to approach to each other to generate the compressive stress in the magnetostrictive rod.