A magnetstriction type actuator is capable of reducing an input power loss and increasing an output, which actuator is reduced in size and is applicable to a vibrator. The actuator comprises: displacement generating means formed of a magnetic substance having magnetostriction; a movable member fixed to the displacement generating means, which movable member is movable in the direction of displacement of the displacement generating means; first magnetic field generating means, provided around the displacement generating means, for applying a magnetic field to the displacement generating means and second magnetic field generating means for applying a magnetic bias; a magnetic circuit component for constituting, along with the movable member, a main part of a closed magnetic circuit, within which magnetic circuit component the displacement generating means and the magnetic field generating means are stored; and an elastic member, disposed within the magnetic circuit component, for applying a compression force to the displacement generating means via the movable member in the direction of displacement of the displacement generating means.