PURPOSE: To provide a noise shaper whose output signal is always made zero when an input signal is zero.

CONSTITUTION: The noise shaper 100 composed of integration circuits 12, 15 of one or more stages, a ternary quantizer 17 outputting 0 and ±1, and a feedback circuit is provided with the connection used for inputting the input signal of the noise shaper 100 and one or more output signals from a feedback circuit to the integration circuits 12, 15, the connection used for inputting an output signal from the integration circuits 12, 15 to the quantizer 17, and the connection between the quantizer 17 and the output terminal 2 of the noise shaper 100 and is further provided with a means for making an incomplete integrator action of at least one stage of the integration circuits 12, 15 which is realized through the addition between current data and a positive constant smaller than one in the data stored before one sample delay so long as one sample delay data being the output of the quantizer are zero. An output signal is always made zero when the input signal is zero without losing the S/N characteristic.