A method for manufacturing a lower substrate of a liquid crystal display device is disclosed. The method comprises the steps of: (a) forming a patterned first metal layer, a first insulating layer, a patterned second metal layer and a second insulating layer on a substrate in sequence; (b) coating a transparent electrode layer and a negative photo resist layer on the second insulating layer; (c) irradiating the photo resist layer from the second surface of the substrate; (d) irradiating the photo resist layer from the first surface of the substrate, wherein part of the photo resist layer superposed over the second metal layer is covered by a mask; and (e) removing un-reacted photo resist and patterning the transparent electrode.