The class D amplifier comprises a differential signal output unit for outputting differential signals from voice signals which are input from the input terminal, and the P-side and the N-side charge balanced type class D amplifiers to which the differential signals are output. Each charge balanced type class D amplifier comprises a PWM waveform generation circuit which is comprised of an integrating amplifier and a Schmitt trigger circuit, a level shift circuit for shifting the level of the PWM signals, an output buffer for amplifying the level-shifted signals, and a feedback circuit for feeding back the output of the output buffer negatively to the integrating amplifier. The feedback circuit is constructed such that the feedback amount is variable depending on HIGH or LOW of the output of the output buffer by selecting a predetermined resistance depending on HIGH or LOW.