PURPOSE: To obtain a mixer circuit capable of adjusting dispersion in the characteristic of a FET by adopting only one polarity of a DC bias deciding an operating point of the FET.

CONSTITUTION: A DC bias voltage -VG is applied to a gate G of a FET together with a radio signal through an impedance matching circuit 11 and a local carrier LOin is inputted directly to a drain D through a filter 22 and an impedance matching circuit 23. The FET is operated in an unsaturation region of a drain current Id so that the local carrier is rectified and a self- rectifier current flows to a source S connecting to ground from the drain. The dispersion in the statistic characteristic of the FET is compensated by changing a sum (VB+VD-VG) of a built-in voltage VB of the Rate deciding an intermediate frequency component IdIF included in a drain current Id changed through the dispersion, a DC bias voltage +VD and a DC bias voltage -VG of the Sate G through the chance in the DC bias voltage -VG of the gate G.