Wirings each having a side face with a different angle, which is made accurately, in a desired portion over one mother glass substrate are provided without increasing the steps. With the use of a multi-tone mask, a photoresist layer is formed, which has a tapered shape in which the area of a cross section is reduced gradually in a direction away from one mother glass substrate. At the time of forming one wiring, one photomask is used and a metal film is selectively etched, whereby one wiring having a side face, the shape (specifically, an angle with respect to a principal plane of a substrate) of which is different depending on a place, is obtained.