In one embodiment, an actuator has a movable member, a frame, and first and second electrodes. Each of the first electrodes has a pair of first and second planes perpendicular to a third direction which is orthogonal to the first and the second directions approximately. The second electrodes are provided alternately with the first electrode respectively and with a distance from the first electrode. Each of the second electrodes has a pair of third and fourth planes perpendicular to the third direction. The first and the second planes have a deviation in the third direction with respect to the third and the fourth planes, respectively. The amount of the deviation is larger than a maximum value of the amount of displacement of the movable member in the third direction. The amount of displacement is produced by gravity when a component of the gravity in the third direction is maximum.