To provide a mixer circuit and a frequency conversion circuit that can ensure dynamic range, has a high electrostatic surge resistance, and can be made small in size, low in voltage and in power consumption.

This frequency conversion circuit 1 has a mixer circuit 50 and a local oscillation circuit 60. The local oscillation circuit 60 generates local oscillation signals S4, S5. This mixer circuit 50 has a 1st nonlinear active circuit 50a and a 2nd nonlinear active circuit 50b, mixes local oscillation signals S4, S5 with IF signals S6, S7 to convert the frequency of the local oscillation signals into the frequency of the IF signals through a nonlinear active function. The mixer circuit 50 outputs a current signal from resistive elements R1, R2, R5, and R6. As a result, a load resistor with a large resistance is not required, and the dynamic range by its voltage effect will not be narrowed. Transistors(TRs) Q3, Q10 acting as a signal infiltration path preventing circuit prevent output dynamic range of the mixer circuit 50 from becoming narrow. Since a plurality of TRs configure a differential pair circuit, the electrostatic surge resistance can be improved.