A S/N enhancer using the magnetostatic wave signal. The S/N enhancer comprises a balun coupler for dividing an input signal into a first and second signals having the same power, the second signal having the phase difference of 180 degree with respect to the first signal; a saturation magnetostatic wave filter for receiving the first signal output from said balun coupler, converting that into a magnetostatic wave signal, and oppositely converting the magnetostatic wave signal, wherein the power of the magnetostatic wave signal is saturated if the first signal has the power of equal to and more than that of a noise signal; a linear magnetostatic wave filter for receiving the second signal from said balun coupler, converting that into a magnetostatic wave signal, and oppositely converting the magnetostatic wave signal, wherein the received second signal is converted into the magnetostatic wave signal having an energy linear to the power of the input signal; and a power synthesizer for synthesizing the respective signals output from said saturation magnetostatic wave filter and said linear magnetostatic wave filter.