needs to be increased by one from that of fig3 a when the resistance values of the resistor elements are equal to each other the reference voltages input to each of the switches of the higher order selector 44 have a voltage value that sequentially changes by a fixed voltage difference expressed by vt u2212 vb n when the resistance values of the resistor elements are different from each other the reference voltages have a value that differs according to changes in the resistance value the higher order selector 44 selects two reference voltages having voltage values corresponding to the input higher order bits and having a voltage difference maintained at the fixed voltage difference from the n reference voltages generated in the higher order resistor string 45 the higher order selector 44 then outputs the two reference voltages the lower order selector 47 applies the two reference voltages to both ends of the lower order resistor string incorporated in the lower order selector 47 and subdivides the potential difference to generate 2 m voltages the lower order selector 47 selects one analog voltage corresponding to the input lower order bits from the 2 m voltages the lower order selector 47 then outputs the analog voltage the analog voltages output from the lower order selectors 47 are passed through the buffer amplifiers 48 further processed as required and then input from the data output terminals tdo to the respectively corresponding signal lines the data lines 12 1 to 12 4 in fig4 to.