A thin film transistor substrate includes a thin film transistor, a source wire, an upper-layer source wire, and a pixel electrode. The thin film transistor includes: a source electrode and a drain electrode located to be spaced from each other on the same plane; a semiconductor film located to straddle those electrodes; an insulating film located to cover at least the source electrode, the drain electrode, and the semiconductor film; an upper-layer source electrode and an upper-layer drain electrode located on the insulating film and respectively connected to the semiconductor film through contact holes; and a gate electrode located below or above the semiconductor film. The source wire extends from the source electrode. The upper-layer source wire extends from the upper-layer source electrode. The pixel electrode is electrically connected to the drain electrode.