There is provided a complementary metal oxide semiconductor (CMOS) power amplifier including: a load unit connected between an operating voltage supply terminal and an output terminal; an amplifying unit formed as a cascode structure between the load unit and a ground, amplifying a power of an input signal input through an input terminal and outputting the amplified signal through an output terminal; and a threshold voltage control unit varying a threshold voltage of the amplifying unit according to a magnitude of the input signal input through the input terminal.
