A semiconductor device includes: a plurality of input circuits each of which receives one of an analog signal and a digital signal, the input circuits being supplied a power supply; a selector that selects one of the input circuits; and an analog-to-digital (AD) converter that performs AD conversion of an analog signal input to the selected input circuit. After the selector selects one of the input circuits, the selector selects another of the input circuits. When the selector selects one of the input circuits and one digital signal of others of the input circuits is changed, the selector does not select another of the input circuits.