A bipolar electrode is composed of a first active material layer which is, for example, a positive electrode active material layer formed to include a first active material on one side of a collector, and a second active material layer which is, for example, a negative electrode active material layer formed to include a second active material with less compressive strength than that of the first active material on the other side of the collector. Then, a density adjusting additive which is an additive material with larger compressive strength than that of the second active material is included in the second active material layer.