To provide a de-emphasis circuit capable of effectively performing de-emphasis in a 1-bit signal switching amplifier.

A 1-bit amplifier 1 is provided with the de-emphasis circuit so as to de-emphasize signals after 1-bit signals f generated in a ΔΣ modulation 1-bit conversion circuit 2 are amplitude-amplified in a switching amplifier circuit 3 and outputted as switching signals g until reproducing signals h are outputted to reproducing signal driving equipment K by a demodulation circuit 4, the signals of the demodulation circuit 4 in this case. A pre-emphasis detection circuit 5 detects an emphasis detection code i from an audio signal source S and outputs the presence/absence and the kind of pre-emphasis by detection signals j and the de-emphasis circuit switches the presence/absence and the kind of the de-emphasis by an operation of a relay circuit 6.