A thin film transistor (TFT) device including a first electrode including at least one of a gate, a source and a drain formed on a transparent insulating substrate, an insulating film layer covering both the first electrode and the transparent insulating substrate, and a transparent film electrode formed on the insulating film layer. The first electrode includes a first layer made of pure Al or Al alloy and a second layer, formed by an impurity selected from one of N, O, Si and C, added to the Al or Al alloy. The second layer of the first electrode is provided at an interconnection between the transparent film electrode and the first layer of the first electrode.