A semiconductor device having favorable electrical characteristics is provided. The semiconductor device includes a first oxide; a first conductor and a second conductor over the first oxide; a first insulator over the first conductor; a second insulator over the second conductor; a second oxide provided over the first oxide and being in contact with the side surface of the first conductor and the side surface of the second conductor; a third oxide provided over the second oxide and including regions in contact with the side surface of the first insulator and the side surface of the second insulator; a third insulator over the third oxide; and a third conductor over the third insulator.