In order to provide a mixer capable of extracting a high multiplication signal and which has a reception band-pass filter function, a magnetoresistance effect element is provided that includes a pinned magnetization layer, a free magnetization layer, and a non-magnetic spacer layer disposed between the pinned magnetization layer and the free magnetization layer. This allows for a frequency converter which implements a desired band-pass filter by controlling a magnetic field applied by a magnetic-field applying unit to be provided.