The class D amplifier according to an embodiment of the invention comprises a voltage control current source circuit for current--converting voice voltage signals Sin to be input to two signals with different polarities, capacitance elements for integration for storing the electric charge of each of the current--converted signals and feedback signals respectively, hysteresis comparators for PWM conversion for comparing the potential of the capacitance elements for integration and reference potential respectively, output buffers for amplifying the output thereof respectively, and constant current source feedback circuits for feeding back the output thereof respectively.