The present invention improves a productivity in growing an a-Si film in a thin film transistor and to obtain an excellent thin film transistor characteristic. More specifically, disclosed is a thin film transistor in which an amorphous silicon film 2, a gate insulating film 3 and a gate electrode are sequentially stacked on an insulating substrate 1. The amorphous silicon film 2 includes a low defect-density amorphous silicon layer 5 formed at a low deposition rate and a high deposition rate amorphous silicon layer 6 formed at a deposition rate higher than that of the low defect-density amorphous silicon layer 5. The low defect-density amorphous silicon layer 5 in the amorphous silicon film 2 is grown closer to the insulating substrate 1, and the high deposition rate amorphous silicon layer 6 is grown closer to the gate insulating film 3.