An oxide semiconductor thin film transistor includes a source, a drain, a channel layer, an insulation layer, a first conductor and a second conductor. The channel layer is disposed between the source and the drain, and separated from the source and the drain. The insulation layer covers the source, the drain and the channel layer. The first conductor is at least disposed in a first opening of the insulation layer so as to touch the source and the channel layer. The second conductor is at least disposed in a second opening of the insulation layer so as to touch the drain and the channel layer.