Using the product effect of electrostrain and piezopermeability, a novel and heterotypic composite of magnet/ferroelectrics has been developed and its electromagnetic coupling has been investigated. Under a constant electric field of 5 kV/cm, about 40% electric-field-induced changes of inductance and impedance have been observed over a wide range of frequency for the composites. The electric-field dependent inductance and impedance show a joint behavior of ferromagnetic and ferroelectric relaxation. Analysis shows that all the behaviors observed can be ascribed to the electric field-controlled variation of the internal stress in the composite.