A liquid ejection head substrate includes an electrode pad for receiving driving power for liquid ejection from an outside, the electrode pad including at least a conductor layer and a layer of gold. A portion of the conductor layer has an opening region, and an upper layer portion in a laminating direction above the conductor layer including the opening region has at least the layer of gold. An external connection portion connected to the outside is provided on top of the layer of gold corresponding to the opening region of the conductor layer.