A liquid crystal display device includes a semiconductor layer which is formed of a poly-Si layer and an a-Si layer and formed above a gate electrode with a gate insulating film interposed therebetween. A source electrode or a drain electrode is formed above the semiconductor layer. An n+Si layer is formed between the source electrode or the drain electrode and the semiconductor layer. Since ends of the source electrode or the drain electrode are formed inside ends of the semiconductor layer, leak current at the ends of the semiconductor layer can be reduced.