An apparatus and an operating method of an asymmetric Doherty power amplifier. A Doherty power amplifier apparatus includes a power divider configured to provide a power signal to a carrier amplifier and a peaking amplifier. The apparatus also includes the carrier amplifier configured to amplify a power of the signal input from the power divider. The apparatus further includes the peaking amplifier configured to have a maximum output power magnitude different from the carrier amplifier and amplify the power of the signal input from the power divider. The apparatus still further includes at least two offset transmission lines disposed at ends of the carrier amplifier and the peaking amplifier and configured to regulate a load impedance. The apparatus also includes an output combiner configured to combine and output outputs of the carrier amplifier and the peaking amplifier of different sizes.