The present invention provides a semiconductor device in which an adjustable range of a resistance value of a variable resistance circuit is large. The semiconductor device has an output buffer including a plurality of sets of resistance elements and a plurality of sets of transistors, a plurality of replica circuits, and a plurality of sets of operational amplifiers, and drain currents of the plurality of sets of transistors are adjusted so that output impedances of the output buffer become predetermined values. Therefore, even in the case where the resistance values of the resistance elements largely fluctuate due to fluctuations in manufacture process and the like, the output impedances can be set to predetermined values.