The semiconductor device includes a first insulating layer; a first oxide semiconductor; a first insulator containing indium, an element M (M is gallium, aluminum, titanium, yttrium, or tin), and zinc; a second oxide semiconductor; a source electrode layer; a drain electrode layer; a second insulator containing indium, the element M, and zinc; a gate insulating layer; and a gate electrode layer. The first and second oxide semiconductors each include a region with c-axis alignment. In the first and second oxide semiconductors, the number of indium atoms divided by sum of numbers of the indium atoms, element M atoms, and zinc atoms is ⅓ or more. In the first insulator, the number of zinc atoms divided by sum of the numbers of indium atoms, element M atoms, and zinc atoms is ⅓ or less.