A thin film transistor includes: an insulating layer; a gate electrode provided on the insulating layer; a gate insulating film provided on the gate electrode; a semiconductor layer provided on the gate insulating film, the semiconductor layer being formed of oxide; source and drain electrodes provided on the semiconductor layer; and a channel protecting layer provided between the source and drain electrodes and the semiconductor layer. The source electrode is opposed to one end of the gate electrode. The drain electrode is opposed to another end of the gate electrode. The another end is opposite to the one end. The drain electrode is apart from the source electrode. The channel protecting layer covers at least a part of a side face of a part of the semiconductor layer. The part of the semiconductor layer is not covered with the source and drain electrodes above the gate electrode.