Disclosed is an interpolative A/D converter for converting an over-sampled analog signal into a digital signal without the occurrence of over slope distortions, wherein the difference between the analog input signal and an analog feedback signal derived from the converter output through D/A conversion is integrated, the integrated output is compared with several reference voltages and, after being converted into a digital signal, the comparison result is integrated in a digital manner to complete a digital output signal of the A/D converter.