A liquid crystal display device intended for increasing the ON-current of a TFT in the pixel while suppressing variation of the ON-current, in which a semiconductor layer and a first n+-a-Si layer in the TFT are formed continuously by plasma CVD. The semiconductor layer and the first n+-a-Si layer are patterned simultaneously. Then, a second n+-a-Si layer is formed so as to cover the upper surface of the first n+-a-Si layer and the side portion of the semiconductor layer. The ON-current can be increased and variation of the ON-current of the TFT can be decreased by forming the first n+-a-Si layer continuously over the semiconductor layer.