PURPOSE: To eliminate the DC output offset voltage and to improve the DC stability, by providing an FET in parallel to another FET of a cascode amplifying circuit comprising said FET and a transistor and then applying the negative feedback to the above-mentioned FET from the transistor.

CONSTITUTION: For a cascode amplifying circuit, an FET3 is cascode-connected to a transistor TR6 and the drain voltage is decided by the voltage of a power supply 7. An FET11 which eliminates the DC offset voltage is connected in parallel to the FET3, and the drain of the FET11 is connected to a constant current source 5. While the gate of the FET11 is grounded via a capacitor 13, and at the same time the collector of the TR6 is connected to a constant current source 8 via a resistance 14.