To provide a method for manufacturing an array substrate of a liquid- crystal display device of improved reliability, without decreasing an open area ratio, while reducing the manufacturing cost.

A scanning line 14 is formed on a substrate 10, on which a first insulation film 32, a second insulation film 34, a semiconductor film 36 and a metal film are deposited. The metal thin film, semiconductor film, and second insulating film are patterned, based on the same pattern until the first insulating film is exposed, to form a signal wire, a source electrode, and a drain electrode. A third insulation film covering the scanning line, source electrode, drain electrode, and signal wire is deposited so that a contact hole is formed on the third insulation film over the source electrode. Further, a pixel electrode 28 is formed which is connected electrically to the source electrode via the contact hole.