The yield of a manufacturing process of a semiconductor device is increased. The mass productivity of a semiconductor device is increased. A semiconductor device is manufactured by forming a first material layer over a substrate; forming a second material layer over the first material layer; and separating the first material layer and the second material layer from each other; and heating the first material layer and the second material layer that are stacked before the separation. The first material layer includes a gas containing hydrogen, oxygen, or hydrogen and oxygen (e.g., water) in a metal oxide, for example. The second material layer includes a resin. The first material layer and the second material layer are separated from each other by a break of a hydrogen bond. Specifically water is separated out at the interface or near the interface, and then adhesion is reduced due to the water present.