A semiconductor device is manufactured by forming a gate electrode layer over a substrate having a light transmitting property; forming a gate insulating layer over the gate electrode layer; forming a photocatalyst material over the gate insulating layer; immersing the photocatalyst material in a solution containing a plating catalyst material and selectively exposing the photocatalyst material to light transmitted through the substrate in the solution containing the plating catalyst material with the use of the gate electrode layer as a mask to adsorb or deposit the plating catalyst material onto the light-exposed photocatalyst material; immersing the plating catalyst material in a plating solution containing a metal material to form a source electrode layer and a drain electrode layer on the surface of the photocatalyst material adsorbing or depositing the plating catalyst material; and forming a semiconductor layer over the source electrode layer and the drain electrode layer.