Abstract: A magnetodistortive actuator includes an elongated active component of a magnetodistortive material mounted on a support and having a stationary and a movable end portion. At least one permanent magnet applied a permanent magnetic bias to the active component to bring it to a desired point of its stress/field characteristic line. The strength of that portion of the magnetic field of the permanent magnet that acts on the active component is selectively varied by changing the magnetic reluctance of a body that is accommodated in a space interposed between the permanent magnet and the active component. The active component is further subjected to a variable magnetic field generated by a solenoid surrounding the active component, so that the active component is selectively shortened and lengthened around its length corresponding to the desired point, with attendant movement of the movable end portion relative to the support.