There is provided a battery including a positive electrode, a negative electrode, a separator at least including a porous film, and an electrolyte. The positive electrode includes a positive electrode current collector having a pair of surfaces, and a positive electrode active material layer provided on each of the surfaces of the positive electrode current collector. The positive electrode active material layer contains a positive electrode active material. The positive electrode active material layer has an area density S [mg/cm2] more than or equal to 30 mg/cm2. The porous film included in the separator has a porosity ε [%] and an air permeability t [sec/100 cc] which satisfy a predetermined formula.