A high frequency amplifier includes a constant voltage driven amplifier 1 using as its amplifying element a bipolar transistor 7 with its base biased by a constant voltage, and a constant current driven amplifier 2 using as its amplifying element a bipolar transistor 8 with its base biased by a constant current. The idle current of the constant current driven amplifier 2 is set at a low value. In accordance with the idle current, the idle current of the constant voltage driven amplifier 1 is adjusted, and the two amplifiers are combined in parallel.