A feedforward-type linear power amplifier directly compares amplitude and phase of a signal applied to one input end of a first signal canceler with amplitude and phase of a signal applied to another input end of the first signal canceler, and according to the comparison results, controls a first variable attenuator and a first variable phase shifter disposed in a pre-stage of the first signal canceler so that the first signal canceler extracts only the intermodulation distortion signals generated while a main power amplifier amplifies the RF input signal. Then, the linear power amplifier directly compares amplitude and phase of the intermodulation distortion signal on a main path with amplitude and phase of the intermodulation distortion signal on a sub path, and according thereto, controls a third variable attenuator and a third variable phase shifter to cancel the intermodulation distortion signals contained in the RF output signal of the main power amplifier.