NOVELTY - A lithium ion secondary battery has electrical power collector, and porous layer containing positive electrode active material particles having shell portion and hollow portion. Ratio of hollow portion in apparent cross-sectional area of positive electrode active material particles is 23% or more. When thickness of shell portion in arbitrary positions of shell portion is made into shortest distance from arbitrary positions of inner surface of shell portion to outer surface of shell portion, the thickness of shell portion is 2.2 mu m or less.    USE - Lithium ion secondary battery used as power supply for plug-in hybrid car and electric vehicles.    ADVANTAGE - The lithium ion secondary battery has excellent charging/discharging characteristics and high output, and low charge amount.    DETAILED DESCRIPTION - A lithium ion secondary battery has an electrical power collector, and porous positive electrode active material layer containing positive electrode active material particles, electroconductive material, and binder. The porous positive electrode active material layer is maintained at the electrical power collector. The positive electrode active material particles have shell portion containing lithium transition metal oxide, hollow portion formed inside the shell portion, and through-hole which penetrates the shell portion. The ratio of hollow portion in the apparent cross-sectional area of positive electrode active material particles is 23% or more. When thickness of shell portion in the arbitrary positions of the inner surface of the shell portion is made into the shortest distance from the arbitrary positions of inner surface of the shell portion to the outer surface of the shell portion, the thickness of the shell portion is 2.2 mu m or less in the average of the positive electrode active material layer. INDEPENDENT CLAIMS are included for the following:    (1) granular material of positive electrode active material particles; and    (2) manufacture of positive electrode active material particles.