The present invention provides a method by which a thin film process can be conducted simply and accurately without using resist. Further, the present invention provides a method of manufacturing semiconductor devices at low cost. A first layer is formed over a substrate, a peeling layer is formed over the first layer, the peeling layer is selectively irradiated with a laser beam from the peeling layer side to reduce adhesiveness of a part of the peeling layer. Next, the peeling layer in the part with reduced adhesiveness is removed, and the left portion of the peeling layer is used as a mask to selectively etch the first layer.