Disclosed is a method for fabricating a liquid crystal display device comprising: providing a first substrate having a pixel portion and a pad portion; sequentially laminating a gate insulating layer, a semiconductor layer and a first conductive layer on the first substrate where a gate electrode is formed; forming a first PR pattern, which is patterned relatively thin on a channel region of a transistor to be formed, on the first conductive layer with a half-tone mask; patterning the first conductive layer with the first PR pattern; forming a second PR pattern which is aligned with an outer periphery of the first conductive layer by performing a first ashing process on the first PR pattern; patterning the semiconductor layer using the second PR pattern; forming source/drain electrodes using the second PR pattern; forming a passivation layer and a pixel electrode on the first substrate; attaching a second substrate to the first substrate; and forming a liquid crystal layer between the first substrate and the second substrate.