NOVELTY - A positive electrode active material has a diffraction peak which shows a halite-type layered structure at 20-23 degrees , 35-40 degrees (101), 42-45 degrees (104), and 64-65 (108)/65-66 (110) in X-ray diffraction determination, and comprises lithium nickel manganese cobalt oxide composition.    USE - Active material is used for positive electrode for nonaqueous electrolyte secondary battery (all claimed) e.g. lithium-ion secondary battery used for power supply device for hybrid vehicle, electric vehicle and fuel cell electric vehicle, and mobile telephone.    ADVANTAGE - The positive electrode active material effectively reduces the elution of transition metal during charging and discharging of battery. The nonaqueous electrolyte secondary battery containing positive electrode active material has excellent cycling characteristics.    DETAILED DESCRIPTION - A positive electrode active material has a diffraction peak which shows a halite-type layered structure at 20-23 degrees , 35-40 degrees (101), 42-45 degrees (104), and 64-65 (108)/65-66 (110) in X-ray diffraction determination, and comprises lithium nickel manganese cobalt oxide composition of formula: Li1.5(NiaMnbCoc(Li)d(X)e)Oz.    X=Ti, Zr, or Nb;    e=0.01-0.7;    or a+b+c+d+e=1.5;    d=0.1-0.4;    or a+b+c+e=1.1-1.4;and    z=number of oxygen atoms which satisfies atomic valence.    INDEPENDENT CLAIMS are included for the following:    (1) manufacture of positive electrode active material, which involves mixing citrate of titanium, zirconium or niobium and organic acid salt of transition metal having melting point of 100-350 degrees C, dissolving the obtained mixture at 100-350 degrees C, thermally decomposing the obtained molten material at the temperature more than the melting point, and baking the obtained thermolytic material;    (2) positive electrode, which comprises the positive electrode active material; and    (3) nonaqueous electrolyte secondary battery, which comprises a positive electrode, a negative electrode containing insertable/detachable negative electrode active material, an electrolyte layer (13) interposed between the positive electrode and the negative electrode, in which the surface of negative electrode active material is coated with an amorphous carbon layer, and comprises graphite material which is not scale shape, and has BET specific surface area of 0.8-1.5 m2/g and tap density of 0.9-1.2 g/cm3.    DESCRIPTION OF DRAWING(S) - The drawing shows cross-sectional view of non-bipolar-type lithium-ion secondary battery.    Lithium-ion secondary battery (10a)    Negative electrode active material layer (12)    Electrolyte layer (13)    Positive electrode active material layer (15)    Laminate film (22)