A manufacturing method is provided which achieves an SOI substrate with a large area and can improve productivity of manufacture of a display device using the SOI substrate. A plurality of single-crystalline semiconductor layers are bonded to a substrate having an insulating surface, and a circuit including a transistor is formed using the single-crystalline semiconductor layers, so that a display device is manufactured. Single-crystalline semiconductor layers separated from a single-crystalline semiconductor substrate are applied to the plurality of single-crystalline semiconductor layers. Each of the single-crystalline semiconductor layers has a size corresponding to one display panel (panel size).