PURPOSE: To improve the stability, by setting the impedance of a DC cut coupling capacitor between high frequency amplifying stages to 0.06∼0.18Ω in the operating center frequency and suppressing the low frequency coupling even when an output-side load is shorted or opened.

CONSTITUTION: Transistors TRs 11 and 23 of respective amplifying stages of a two-stage high frequency amplifying circuit are coupled, and a value C of a capacitor 18 which cuts the DC is so set that 1/(2πf0C)=0.06∼0.18Ω is true when the center operating frequency of an input signal is denoted as f0. Thus, (for example, the value C of the capacitor is set to about 2,000∼6,000pF when the center operating frequency is 440MHz) the low frequency coupling between TRs 11 and 23 is suppressed even under severe conditions such as the shorting or opening state of the output-side load, and the wide band characteristic is not damaged.