To provide a semiconductor device with a novel structure. The semiconductor device includes a plurality of constant current circuits each given a digital signal. The constant current circuits each include a first transistor to a third transistor. The first transistor has a function of making a first current corresponding to set analog potential flow therethrough. The second transistor has a function of controlling the first current flowing between a source and a drain of the first transistor, in response to the digital signal. The third transistor has a function of holding the analog potential supplied to a gate of the first transistor, by being turned off. The first transistor to the third transistor each include a semiconductor layer including an oxide semiconductor in a channel formation region.