To make analog quantity, which is increased with the increase of a pulse density modulation(PDM) code, completely proportional to a PDM code No., by composing a PD modulator of a PDM circuit and a duty adjusting circuit.

This device is provided with a PDM circuit 3, D/A converting circuit 4 and duty adjusting circuit 5. Then, a PD modulator 6 is composed of these PDM circuit 3 and duty adjusting circuit 5. Therefore, the time duration of logic value '1' is widened and the duration of '0' is narrowed and made equal with the value of analog quantity (DC voltage) when '0' before the logic value '1' is changed into '1'. Thus, since the duty adjusting circuit 5 is connected to the PDM circuit 3, the error of DC voltage to be generated can be corrected corresponding to the existence of rising time of pulse of logic value '1' and the increase of DC voltage can be linearly changed corresponding to the increase of PDM code.