To prevent a short circuit between scanning lines by conduction in an undercut portion arising from reciprocal diffusion of aluminum and silicon composing a bus wiring of the scanning line.

In the scanning line, a scanning signal line bus wiring 9 is composed of an intermediate layer 92 made of aluminum or aluminum alloy laminated with an extension portion of an upper electrode 26 as an upper layer and a lower layer made of a silicon system membrane 24 formed on an interlayer insulation film 14 which is arranged between a data line 8, and between the intermediate layer 92 and the lower layer 24, there is provided a silicon oxide film 95.