A semiconductor device having a large on-state current and high reliability is provided. The semiconductor device includes a first insulator, a first oxide over the first insulator, a second oxide over the first oxide, a third oxide and a fourth oxide over the second oxide, a first conductor over the third oxide, a second conductor over the fourth oxide, a fifth oxide over the second oxide, a second insulator over the fifth oxide, and a third conductor over the second insulator. The fifth oxide is in contact with a top surface of the second oxide, a side surface of the first conductor, a side surface of the second conductor, a side surface of the third oxide, and a side surface of the fourth oxide. The second oxide contains In, an element M, and Zn. The first oxide and the fifth oxide each contain at least one of constituent elements included in the second oxide. The third oxide and the fourth oxide each contain the element M. The third oxide and the fourth oxide include a region where the concentration of the element M is higher than that in the second oxide.