A slide actuator according to the present invention includes: a fixed member; a movable member movable in a predetermined direction with respect to the fixed member; a wall portion of the fixed member disposed in a moving direction of the movable member; a plurality of balls interposed between the fixed member and the movable member and configured to movably support the movable member; a retainer configured to maintain a constant distance between the respective balls; a retainer spring connected between the wall portion and the retainer; and a movable portion spring connected between the movable member and the wall portion, in which the retainer spring is disposed so as to suppress a displacement of the retainer in the moving direction, and the movable portion spring is disposed so as to suppress a displacement of the movable member in the moving direction.