A semiconductor device in which an electrification phenomenon that leads to characteristic fluctuations, element deterioration, or dielectric breakdown is inhibited is provided. A first transistor, a second transistor, a third transistor, and a fourth transistor are included over a substrate; the fourth transistor includes a first conductor, a second conductor, a third conductor, and an oxide semiconductor; the first conductor is electrically connected to the semiconductor substrate through the first transistor; the second conductor is electrically connected to the semiconductor substrate through the first transistor; the third conductor is electrically connected to the semiconductor substrate through the first transistor; and the fourth conductor is electrically connected to the semiconductor substrate through the first transistor.