In a delta-sigma A/D converter provided with plural channels for converting an analog input signal into a digital signal, an adverse influence of an idle tone is reduced in each channel. The delta-sigma A/D converter comprises: a first quantizer which quantizes and outputs a received signal; a first D/A converter which converts an output signal of the first quantizer into an analog signal, and outputs the converted analog signal; a first operation unit which outputs a signal indicative of a difference of the first analog input signal and an output signal of the first D/A converter; a first integrator which integrates an output signal of the first operation unit and outputs the integrated signal; a first dither circuit which generates a first dither signal; and a second operation unit which adds the first dither signal to the output signal of the first integrator and outputs the added signal to the first quantizer.