A highly reliable semiconductor device is provided. The semiconductor device includes a first insulator; a first oxide provided over the first insulator; a second oxide provided over the first oxide; a first conductor and a second conductor provided apart from each other over the second oxide; a third oxide provided over the second oxide, the first conductor, and the second conductor; a second insulating film provided over the third oxide; and a third conductor provided over the second oxide with the third oxide and the second insulating film positioned therebetween. The third oxide contains a metal element and nitrogen, and the metal element is bonded to nitrogen.