A method of separating a lamination body with high yield without damaging the lamination body is provided. Further, a method of manufacturing a lightweight, flexible semiconductor device, which is thin in total is provided. The method of manufacturing the semiconductor device includes: a first step of laminating a metal layer, an oxide layer, a layer containing no hydrogen element, and a lamination body on a first substrate; a second step of forming a photocatalytic layer on a transparent substrate; and a third step of attaching the photocatalytic layer to the surface of the lamination body by using a first adhesive material after the first and second steps, separating the metal layer from the oxide layer, and irradiating light from a side of the transparent substrate so that an interface between the photocatalytic layer and the first adhesive material is separated to remove the first adhesive material.