An 
amplifier circuit capable of suppressing the circuit scale thereof and obtaining an output 
signal with high power efficiency and little 
distortion is disclosed. In this circuit, constant-envelope 
signal generating section (101) generates a plurality of constant-envelope signals from an input 
signal. 
Pilot signal generating section (102) generates a plurality of 
pilot signals associated with the generated plurality of 
constant envelope signals, the plurality of 
pilot signals having predetermined amplitudes, predetermined phases and predetermined frequencies, respectively, the phases and frequencies being different from each other. First addition section (103) and second addition section (104) add the plurality of 
pilot signals to the generated plurality of constant-envelope signals. First 
amplifier (111) and second 
amplifier (112) amplify the plurality of constant-envelope signals to which the plurality of pilot signals are added. Vector adjustment section (105) corrects the amplitude or phase of one of the generated plurality of constant-envelope signals using a signal component included in the amplified plurality of constant-envelope signals and corresponding to the plurality of pilot signals.