An actuator is disclosed which has a driving section driven by means of electro-mechanical displacing members such as a piezoelectric members. The electro-mechanical displacing members are connected to a driving piece at one ends thereof and the driving piece is driven by the composition of displacements of the electro-mechanical displacing members. The movement of the driving piece is transmitted to a driven section. The electro-mechanical displacing members are also connected to a base member at the other ends thereof. A restraining member restrains unnecessary movement of the actuator which is composed of the electro-mechanical displacing members, the driving piece and the base member, thereby insuring stable operation of the actuator.