A positive electrode is provided with: a positive electrode current collector constituted of aluminum as the main component; a positive electrode mixture layer formed on the positive electrode current collector aid containing a lithium-containing transition metal oxide; and a protective layer interposed between the positive electrode current collector and the positive electrode mixture layer. The protective layer contains inorganic particles, a conductive agent, and a binder material. In the positive electrode, the peel strength between the positive electrode current collector and the protective layer is higher than the peel strength between the protective layer and the positive electrode mixture layer.