A power amplifier comprises an amplifier amplifying a high-frequency signal modulated by an input signal. An inverted envelope generates circuit generating an inverted envelope signal by using the input signal or the high-frequency signal The inverted envelope signal having an inverted envelope. A variable gain amplifier adjusts the amplitude of the inverted envelope signal, and a variable delay circuit adjusts a phase of the inverted envelope signal. A control circuit outputs a control signal to the variable gain amplifier and the variable delay circuit based on information about distortion or a signal level of the amplified high-frequency signal. The inverted envelope signal having been adjusted in amplitude or phase is injected to the high-frequency signal or the amplified high-frequency signal. The control circuit controls the variable gain amplifier or the variable delay circuit so that distortion or a signal level of the amplified high-frequency signal is minimum.