A thin film transistor (TFT) located on a thin film transistor substrate includes a first insulating film formed so as to cover a gate electrode, a channel layer that is formed at a position on the first insulating film overlapping the gate electrode and formed of an oxide semiconductor, a second insulating film formed on the channel layer, and a third insulating film formed so as to cover the second insulating film. A source electrode and a drain electrode are formed on the third insulating film. Each of the source electrode and the drain electrode is connected to the channel layer through the corresponding one of contact holes penetrating the second insulating film and the third insulating film.