Disclosed is a Doherty amplifier including a carrier amplifier to perform a signal amplification operation regardless of a level of an input signal, a peaking amplifier to perform an amplification operation, starting from a high power output where a level of an input signal is equal to or greater than a predetermined level, an output combination circuit to combine and output the outputs of the carrier amplifier and the peaking amplifier, and an input division circuit to divide an input signal into the carrier amplifier and the peaking amplifier, the Doherty amplifier including a carrier amplifier output harmonic impedance tuning network installed at a rear end of the carrier amplifier to tune an output harmonic impedance of the carrier amplifier, and a peaking amplifier output harmonic impedance tuning network installed at a rear end of the peaking amplifier to tune an output harmonic impedance of the peaking amplifier.