The present invention provides a method for manufacturing a semiconductor device having high characteristic and reliability. The etching damage during dry etching after forming an electrode or a wiring over an insulating film is prevented. The damage is suppressed by forming a conductive layer so that charged particles due to plasma during dry etching are not generated in a semiconductor layer. Accordingly, it is an object of the invention to provide a method not for generating the deterioration of the transistor characteristic especially in a thin film transistor having a minute structure.