Unnecessary moment in a vibrator is remarkably reduced and the power generation efficiency in capacitance-type vibrational power generation is remarkably improved. A vibrator provided in a variable-capacitance type vibrator has a structure in that one ends of oscillation plates extending in a longitudinal direction thereof sandwiches a mass and the other ends thereof sandwiches a spacer, respectively, wherein the oscillation plates are arranged parallel to each other. A space portion between the oscillation plates and in which the mass and the spacer are not in contact with each other functions as a spring. By holding the mass by the two oscillation plates, the mass can be oscillated while it is in parallel to an opposing electrode. Therefore, generation of unnecessary moment in a direction other than an oscillation direction can be remarkably reduced.