To improve the use efficiency of materials and provide a technique of fabricating a display device by a simple process. The method includes the steps of providing a mask on a conductive layer, forming an insulating film over the conductive layer provided with the mask, removing the mask to form an insulating layer having an opening; and forming a conductive film in the opening so as to be in contact with the exposed conductive layer, whereby the conductive layer and the conductive film can be electrically connected through the insulating layer. The shape of the opening reflects the shape of the mask. A mask having a columnar shape (e.g., a prism, a cylinder, or a triangular prism), a needle shape, or the like can be used.