This positive electrode is characterized by comprising a positive electrode collector, a positive electrode mixture layer that contains a lithium-containing transition metal oxide, and a protective layer that is arranged between the positive electrode collector and the positive electrode mixture layer, and is also characterized in that: the protective layer contains an inorganic compound that has a lower oxidative power than the lithium-containing transition metal oxide; a part of the lithium-containing transition metal oxide penetrates through the protective layer so as to be in contact with the positive electrode collector; and the coverage α of the main surface of the positive electrode collector by the protective layer is 50% or more.