PURPOSE: To obtain a D/A converter having greatly improved linearity, by having a connection on an IC substrate so that the errors are offset for numbers of constant current sources that should be selected by digital data.

CONSTITUTION: The 4-bit digital data MSB, 2nd, 3rd and LSB which are applied to a terminal E control the switches S1∼S4 via a driver A. The accurate current value is measured through a terminal G for each of the constant corrent sources I1∼I15 which and designed as ICs having the same value. One of the sources I1∼I15 that has the current value most approximate to the mean value is connected to the switch S1 via a switch within a switch array F. At the same time, two current sources whose sum current value is double as much as the mean value are connected to the switch S2 in the same way. In the same way, the current sources to be connected to the switches S3 and S4 are decided. Then the switch in the array F is set fixedly. In such constitution, linearity is improved for the analog signal which is obtained through a terminal D.