A motor comprising: a capacitive actuator including a plurality of actuator units and an output cam, wherein each of the plurality of actuator units includes: an expandable element that has capacitive properties; a displacement expansion mechanism that converts displacement of the expandable element into an expanding displacement in a predetermined direction by generating a buckling phenomenon; and an output transmission portion that transmits the output of the displacement expansion mechanism to the output cam, wherein the output cam includes a periodic shape portion with which the output transmission portion is in contact, and wherein the actuator further comprises urging means (11a4) configured to always generate an urging force such that the periodic shape portion and the output transmission portion come into contact with each other, characterized in that each of the plurality of the actuator units includes a spring preload adjustment mechanism which adjusts the urging force so that the urging force is always a positive value and the output transmission portion is pressed against the periodic shape portion by the urging force regardless of a magnitude of the expanding displacement of the expandable element and the presence or absence of a voltage applied to the expandable element. a capacitive actuator including a plurality of actuator units and an output cam, wherein each of the plurality of actuator units includes: an expandable element that has capacitive properties; a displacement expansion mechanism that converts displacement of the expandable element into an expanding displacement in a predetermined direction by generating a buckling phenomenon; and an output transmission portion that transmits the output of the displacement expansion mechanism to the output cam, wherein the output cam includes a periodic shape portion with which the output transmission portion is in contact, and wherein the actuator further comprises urging means (11a4) configured to always generate an urging force such that the periodic shape portion and the output transmission portion come into contact with each other, characterized in that each of the plurality of the actuator units includes a spring preload adjustment mechanism which adjusts the urging force so that the urging force is always a positive value and the output transmission portion is pressed against the periodic shape portion by the urging force regardless of a magnitude of the expanding displacement of the expandable element and the presence or absence of a voltage applied to the expandable element. an expandable element that has capacitive properties; a displacement expansion mechanism that converts displacement of the expandable element into an expanding displacement in a predetermined direction by generating a buckling phenomenon; and an output transmission portion that transmits the output of the displacement expansion mechanism to the output cam, wherein the output cam includes a periodic shape portion with which the output transmission portion is in contact, and wherein the actuator further comprises urging means (11a4) configured to always generate an urging force such that the periodic shape portion and the output transmission portion come into contact with each other, characterized in that each of the plurality of the actuator units includes a spring preload adjustment mechanism which adjusts the urging force so that the urging force is always a positive value and the output transmission portion is pressed against the periodic shape portion by the urging force regardless of a magnitude of the expanding displacement of the expandable element and the presence or absence of a voltage applied to the expandable element.