A thin film transistor array substrate, which can have high mobility of charge and can achieve uniform electrical characteristics for wide display devices, and a method of manufacturing the thin film transistor array substrate, are provided. The thin film transistor array substrate includes an oxide semiconductor layer having a channel and formed on an insulating substrate, a gate electrode overlapping the oxide semiconductor layer, a gate insulating film disposed between the oxide semiconductor layer and the gate electrode, and a passivation film formed on the oxide semiconductor layer and the gate electrode. At least one of the gate insulating film and the passivation film contains fluorine-containing silicon.