A semiconductor device that can extend the range of adaptable sampling rate when performing analog/digital conversion is provided. The semiconductor device includes a plurality of sample-and-hold circuits storing an analog signal and a plurality of converter circuits having a function of converting the analog signal stored in the sample-and-hold circuit into a digital signal. The sample-and-hold circuit includes a switch and a capacitor that is supplied with an analog signal through the switch. The switch includes an oxide semiconductor in a channel formation region.