An organic EL display device has a substrate, a plurality of organic EL elements formed on the substrate and a plurality of thin film transistors formed on the substrate. The transistors are connected to the respective EL elements for controlling current applied to the respective elements. Each of the transistors includes an active layer of semiconductor material, formed on the substrate, a source region and a drain region being formed in the active layer, a source electrode of aluminum material electrically coupled to the source region formed in the active layer, a drain electrode of aluminum material electrically coupled to the drain region formed in the active layer, an insulation layer formed on the active layer, a gate electrode formed on the insulation layer, a first barrier metal layer of titanium nitride containing equal to or less than 50 atm % of nitrogen or titanium, inserted between the source electrode and the source region of the active layer, and a second barrier metal layer of titanium nitride containing equal to or less than 50 atm % of nitrogen or titanium, inserted between the drain electrode and the drain region of the active layer.