1. An amplifying apparatus generating an output signal obtained by amplifying an input signal by amplifying an amplitude component of the input signal including the amplitude component and a phase component, and mixing the amplified amplitude component and the phase component, comprising: a pulse modulator generating a pulse-modulated signal by pulse-modulating and amplifying the amplitude component of the input signal; a low-pass filter filtering the pulse-modulated signal from the pulse modulator, and generating an amplified amplitude signal obtained by amplifying the amplitude component; an error corrector generating a corrected amplitude signal by correcting an error included in the amplified amplitude signal from the low-pass filter by using the amplitude component of the input signal; and a mixing unit generating the output signal by mixing the corrected amplitude signal from the error corrector and the phase component of the input signal, wherein the error corrector detects a difference between the amplitude component and the amplified amplitude signal by using a linear amplifier, generates a pulse signal by pulse-modulating and amplifying a signal of the difference in a second pulse modulator, filters the pulse signal, and subsequently, negatively feeds back the pulse signal to the linear amplifier.