Disclosed is a non-aqueous electrolyte secondary battery having an excellent preservation characteristic at a high temperature and charging/discharging cycle characteristic. A rolled body in which a strip-shape positive electrode and negative electrode are rolled with a separator in-between is provided inside a battery can. The positive electrode contains Li_xMn_2-yMa_yO₄ (where, Ma is at least one element selected from the group consisting of metal elements other than Mn, and B) and LiNi_1-zMb_zO₂ (where, Mb is at least one element selected from the group consisting of metal elements other than Ni, and B). By replacing part of Mn and Ni with other elements, the crystal structure can be stabilized. Thereby, the capacity retention ratio after preservation at a high temperature, and a heavy load discharging power under a high electric potential cutoff can be improved. The mean particle size of particles of the above-mentioned oxides are preferable to be 30 m and below so that an excellent charging/discharging cycle characteristic can be obtained.