A semiconductor device includes an analog circuit with a first delay variation in response to a variation in a power supply potential, and a digital circuit with a second delay variation smaller than the first delay variation. The analog circuit is connected to a first power supply potential. The digital circuit includes a detecting circuit detecting a first delay caused by a first circuit connected to the first power supply potential, and a second circuit generating a control signal to control the analog circuit, the second circuit being connected to a second power supply potential whose potential variation is smaller than the first power supply potential. A second delay caused by the second circuit is controlled in correlation to the first delay.