A battery electrode substrate having excellent mechanical strength and flexibility and being capable of increasing the filling density of a positive electrode active substance and, thereby, achieving a higher capacity battery, a battery electrode formed from the battery electrode substrate, and an alkaline secondary battery including the battery electrode are provided. The battery electrode substrate includes a woven or unwoven fabric and nickel for coating fibers constituting the woven or unwoven fabric, wherein the weight per area of the above-described woven or unwoven fabric is 15 g/m2 or more, and 60 g/m2 or less and the thickness of the above-described woven or unwoven fabric is 1.3 mm or more, and 3.0 mm or less. The battery electrode is formed from the battery electrode substrate, and the alkaline secondary battery includes the battery electrode.