Magnetostrictive transducers use the principle of magnetostriction, in which certain materials expand and contract when in an alternating magnetic field.

The alternating electric energy from the ultrasound generator is firstly converted into an alternating magnetic field through the use of a wire coil. The alternating magnetic field is then used to induce mechanical vibrations at ultrasound frequency in resonating nickel or other magnetostrictive materials, which are then attached to the surface in order to be vibrated. Since magnetostrictive materials behave in the same way as a magnetic field of the other polarity, the frequency of the electric energy applied to the transducer is ½ the frequency of the desired output. The magnetostrictive transducers firstly provide a strong source of ultrasound vibrations for high power applications, such as ultrasound washing.

Due to the mechanical restrictions inherent to the physical size of the hardware, as well as electric and magnetic complications, high power magnetostrictive transducers often operate at frequencies of over 20 KHz. Piezoelectric transducers, on the contrary, can operate very well within the megahertz range. Magnetostrictive transducers are generally less efficient than piezoelectric transducers. This is primarily due to the fact that the magnetostrictive transducer requires a double conversion of energy, from electric to magnetic and then from magnetic to mechanical. A little efficiency is lost in every conversion. Magnetic hysteresis effects also reduce the efficiency of the magnetostrictive transducer.