The present invention provides a compound transmitter having power efficiency characteristics and distortion characteristics superior, over a wide band, to those of a Doherty transmitter, and having fewer elements constituting an RF circuit. The present invention is therefore provided with a compound amplifier (201) for generating a signal (z) (efficiency improving signal) obtained by the amplitude modulation of a carrier signal from an RF modulation signal (a) (main signal); power-modulating, using two power amplifiers (50, 51), a signal (S1) obtained by adding together (a) and (z), and a signal (S2) obtained by subtracting (z) from (a); and setting, as a transmitter output point, the point (p1) where the respective outputs are combined via impedance inverters (60, 61), the efficiency improving signal (z) being generated under conditions in which the size of the envelope of either (S1) or (S2) is fixed.