A magnetostrictive mechanical filter comprising at least one rod of a magnetostrictive material forming a resonance element, a spool surrounding the rod, a field coil the windings of which are wound around the spool, and magnets creating a continuous magnetic field, arranged respectively at the ends of the rod, the rod being held radially in at least three points disposed regularly about the rod in the vicinity of the middle portion thereof, a rib being provided at each fixation point, said rib extending parallel to the generatrices of the rod and being formed on the inner peripheral surface of the spool and integrally molded with said spool.