A power amplifier has improved power added efficiency at high output power. The power amplifier includes: a first transistor for amplifying an input signal input to the base thereof and outputting the amplified signal from the collector thereof; a second transistor with power-supply voltage applied to the collector thereof to supply bias voltage or bias current from the emitter thereof to the base of the first transistor; a third transistor whose collector is connected to the collector of the first transistor to amplify the input signal input to the base thereof and output the amplified signal from a collector thereof; a fourth transistor whose base and collector are connected to supply bias from the emitter thereof to the base of the third transistor; and a first resistor with bias control voltage applied to one end thereof and the other end connected to the bases of the second and fourth transistors.