A peeling method at low cost with high mass productivity is provided. A resin layer having a thickness greater than or equal to 0.1 μm and less than or equal to 3 μm is formed over a formation substrate using a photosensitive and thermosetting material, a transistor including an oxide semiconductor in a channel formation region is formed over the resin layer, the resin layer is irradiated with light using a linear laser device, and the transistor and the formation substrate are separated from each other. A first region and a second region which is thinner than the first region or an opening can be formed in the resin layer. In the case of forming a conductive layer functioning as an external connection terminal or the like to overlap with the second region or the opening of the resin layer, the conductive layer is exposed.