A display device includes a display panel which forms a plurality of sub pixels on a substrate thereof, and a drive circuit which is configured to drive the plurality of sub pixels, wherein the drive circuit has a thin film transistor formed on the substrate, and the thin film transistor has a semiconductor layer made of poly-silicon. The thin film transistor includes: a source electrode, a semiconductor layer and a drain electrode which are formed on the substrate; a gate insulation film which is formed on the source electrode, the semiconductor layer and the drain electrode; a gate electrode which is formed on the gate insulation film and above the semiconductor layer; an insulation film which is formed on the gate electrode; and a metal layer which is formed on the insulation film in a state that the metal layer covers at least a portion of the gate electrode.