PURPOSE: To attain a simple converter at a low cost by constituting the digital- analog converter having a multiplication function of four quadrants type that a digital input signal is inputted non-invertedly or invertedly corresponding to the polarity of an analog input signal.

CONSTITUTION: When the polarity of an analog input signal Vi is positive, the analog input signal Vi is inputted to a D/A converter 10 via a full wave rectifier 16b while keeping the amplitude and polarity as they are. In this case, the output of a polarity discriminator 12 is a low level L. When the polarity of the analog input signal Vi is negative, the analog input signal Vi is rectified by the full wave rectifier 16, the polarity is positive while the amplitude is kept the same and the result is inputted to the D/A converter 10. Since the output of the polarity discriminator 12 is a high level H in this case, the polarity of logic is inverted for the digital input signal by an exclusive OR circuit 14 and the result is inputted to the D/A converter 10 Thus, the polarity of the digital input data is inverted. Then a unipolar D/A converter with comparatively low cost is used.