the present invention relates to a radio frequency amplifier and a method of driving the radio frequency amplifier , and an object of the present invention is to provide a radio frequency amplifier and a method of driving the radio frequency amplifier which are excellent in the controllability at the time of a low power output while keeping the advantage of a high efficiency and give the heating generated by a power loss of such a degree that dewing generated due to over - cooling by the cooling system is not generated at the time of a low power output . the radio frequency amplifier is structured by a variable wave height and variable wave width pulse wave generating circuit 11 that generates a pulse wave having an arbitrary pulse height and pulse width , and a power amplifier 12 that is driven by the rectangular wave .