The method of manufacturing a display device includes preparing a substrate having a first and second area surrounding a portion of the first area, forming a semiconductor layer in the first area, forming a first insulating layer covering the semiconductor layer, forming a gate electrode layer that at least partially overlaps the semiconductor layer, forming a pad electrode layer in the second area, forming a second insulating layer covering the gate electrode layer, forming contact holes that at least partially expose the semiconductor layer and the gate electrode layer, and forming a conductive layer positioned in the contact holes and including a first and second layer. The forming of the conductive layer includes forming a first layer material and a second layer material, and removing a portion of the first layer material and a portion of the second layer material to expose the second insulating layer.