It is an object of one embodiment of the present invention to manufacture a light-emitting display device by simplifying a manufacturing process of a transistor, without an increase in the number of steps as well as the number of photomasks as compared to those in the conventional case. A step for processing a semiconductor layer into an island shape is omitted by using a high-resistance oxide semiconductor which is intrinsic or substantially intrinsic for the semiconductor layer, used to form transistors. Formation of an opening in the semiconductor layer or an insulating layer formed over the semiconductor layer and etching of an unnecessary portion of the semiconductor layer are performed at the same time; thus, the number of photolithography steps is reduced.