NOVELTY - The battery has an electrode body provided with a positive electrode active material layer (223) held at a positive electrode electrical power collector (221). Ratio of average particle diameter of the positive electrode active material particle (610a) contained in a surface region (225a) to one fifth of thickness (A) of a surface to the active material layer is between 1.2 and 4 with respect to average particle diameter of an interior area (225b). Particle porosity of the material particle contained in the surface region is smaller than that of the particle contained in the interior area.    USE - Secondary battery i.e. lithium ion secondary battery, for use in a motor vehicle. Can also be used as a nickel-hydrogen battery, a nickel cadmium battery and an electrical double layer capacitor.    ADVANTAGE - The battery allows the particle porosity of the active material particle contained in the surface region to be smaller than that of the active material particle contained in the interior area, so that the gas emitted in the internal layer at time of overcharge goes through a gap of the surface layer to infiltrate electrolyte solution, thus supplying gas forming agent rapidly by consuming the gas forming agent exists previously in the positive electrode active material, and hence ensuring more appropriate gas generated amount to operate an electric current interruption mechanism appropriately in short time during overcharge state. The positive electrode active material particle is provided as a perforated hollow structure, so that the electrolyte solution penetrates through surroundings of the positive electrode active material particle and through a hollow part inside of the positive electrode active material particle in the positive electrode active material layer, thus performing cell reaction and discharge and occlusion of lithium ions smoothly, and hence restraining resistance increase of the battery, while improving performance of discharge of the battery.    DETAILED DESCRIPTION - The surface region is provided with electrode pore diameter of 0.5 micrometer or more.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross sectional view of a positive electrode active material layer.    Thickness of positive electrode active material layer (A)    Positive electrode sheet (220)    Positive electrode electrical power collector (221)    Positive electrode active material layer (223)    Surface region (225a)    Interior area (225b)    Positive electrode active material particle (610a)