A thin film transistor substrate capable of appropriately maintaining driving performance even when there is a difference between manufacturing processes and a method of manufacturing the same. The thin film transistor substrate includes: a gate electrode formed on an insulating substrate; a semiconductor layer formed on the gate electrode; and a plurality of thin film transistors each having a source electrode and a drain electrode that are formed on the gate electrode and the semiconductor layer so as to be spaced apart from each other. At least one of the plurality of thin film transistors is a dummy thin film transistor that does not have the semiconductor layer between the source electrode and the drain electrode.