To provide a D/A(digital/analog) converter that can obtain a high resolution at a low cost with high accuracy.

The digital/analog converter can attain processing of n-bit data at both positions of a switch 6, that is a position of a lower reference voltage input terminal 4 and a position of an upper reference voltage input terminal 3. When an analog output 7 is desirably gradually increased, the switch 6 is placed at the position of the lower reference voltage input terminal 4 and the LSB of data is increased from 0. When the analog output 7 reaches a half of a level at the upper reference voltage input terminal 3, the switch 6 is changed over to the position of the upper reference voltage input terminal 3, and the LSB is simultaneously set to 0 and then if the LSB is again increased, this processing is equivalent to that the resolution of a digital/analog conversion section 2 is increased by 1 bit. When gradually decreasing the LSB, the LSB is gradually decreased from the MAXLSB, and when the analog output 7 reaches a half of a level at the upper reference voltage input terminal 3, the switch 6 is changed over to the position of the lower reference voltage input terminal 4, the LSB is set to the MAXLSB and then the LSB is again decreased.