NOVELTY - An active material contains nickel, manganese, and lithium-containing transition metal oxide having close-packed structure and hexagonal crystal structure. The atomic ratio of number-of-moles of lithium contained in transition metal oxide (MLi) and number-of-moles of transition metal oxide (MT) of lithium-containing transition metal oxide is 1 or more. The X-ray diffraction pattern of the crystal structure has a peak (P003) belonging to (003) plane and a peak (P104) belonging to (104) plane.    USE - Active material is used for nonaqueous electrolyte secondary battery (claimed) used as power supply for electric power storage, electric vehicle and drive of electronic device such as notebook personal computer, mobile telephone, and digital still camera.    ADVANTAGE - The active material provides nonaqueous electrolyte secondary battery having excellent load characteristics, battery characteristics, capacitance, electrochemical characteristics, charging/discharging cycling characteristics and durability.    DETAILED DESCRIPTION - An active material contains nickel, manganese, and lithium-containing transition metal oxide having close-packed structure and hexagonal crystal structure. The atomic ratio of number-of-moles of lithium contained in transition metal oxide (MLi) and number-of-moles of transition metal oxide (MT) of lithium-containing transition metal oxide is 1 or more. The X-ray diffraction pattern of the crystal structure has a peak (P003) belonging to (003) plane and a peak (P104) belonging to (104) plane. The integrated intensity ratio (I003/I104) of the peak (P003) and peak (P104) changes reversibly depended on the occultation and emission of lithium by the transition metal oxide within the range of 0.7-1.5 linearly and continuously. The lithium-containing transition metal oxide contains oxide containing nickel and manganese, as a precursor oxide. The active material further contains element chosen from cobalt, iron, zinc, aluminum, magnesium, strontium, yttrium and/or ytterbium. An INDEPENDENT CLAIM is included for manufacture of the active material.