An actuator 100 of the type employing a two-degree-of-freedom vibration system includes: a pair of first mass portions 1, 11; a second mass portion 2 provided between the pair of first mass portions 1, 11; a pair of supporting portions 3, 3 for supporting the pair of first mass portions 1, 11 and the second mass portion 2; at least a pair of first elastic connecting portions 4, 4 which respectively connect the first mass portions 1, 11 to the supporting portions 3, 3 so that each of the first mass portions 1, 11 can rotate with respect to the supporting portions 3, 3; and at least a pair of second elastic connecting portions 5, 5 which respectively connect the second mass portion 2 to the first mass portions 1, 11 so that the second mass portion 2 can rotate with respect to the first mass portion 1, 11. Each of the first mass portions 1, 11 is driven by the application of an alternating voltage, causing the second mass portion 2 to rotate.