The present invention provides a thin film transistor substrate realizing reduced interlayer short-circuit defects in a capacitor, and a display device having the thin film transistor substrate. The thin film transistor substrate includes: a substrate; a thin film transistor having, over the substrate, a gate electrode, a gate insulating film, an oxide semiconductor layer, and a source-drain electrode in order; and a capacitor having, over the substrate, a bottom electrode, a capacitor insulating film, and a top electrode made of oxide semiconductor in order.