NOVELTY - A nonaqueous electrolyte secondary battery has spiral-shaped wound component obtained by interposing strip-shaped separator between strip-shaped positive electrode and strip-shaped negative electrode. The strip-shaped positive electrode has positive electrode active material layer formed using lithium-transition metal composite oxide of spinel structure which is obtained by baking raw material mixture, and having lithium-niobium-boron complex oxide as positive electrode active material, and is formed on at least one surface of strip-shaped positive electrode collector.    USE - Nonaqueous electrolyte secondary battery. Uses include but are not limited to mobile telephone, notebook computer, digital camera, electric vehicle, calculator, pager, tape recorder, copier, electric shaver and radio.    ADVANTAGE - The nonaqueous electrolyte secondary battery has high electrode density, and excellent cyclic characteristics, storing characteristics and load characteristics.    DETAILED DESCRIPTION - A nonaqueous electrolyte secondary battery has spiral-shaped wound component obtained by interposing a strip-shaped separator between a strip-shaped positive electrode and a strip-shaped negative electrode. The strip-shaped positive electrode has a positive electrode active material layer formed using lithium-transition metal composite oxide of spinel structure which is obtained by baking a raw material mixture, and having lithium-niobium-boron complex oxide as a positive electrode active material, and is formed on at least one surface of a strip-shaped positive electrode collector. The raw material mixture is obtained by mixing compound containing lithium, manganese, boron, and niobium in predetermined ratio. The strip-shaped negative electrode has a negative electrode active material layer including metallic lithium, lithium alloy, carbon material which can occlude-discharge a lithium ion or the compound which can occlude-discharge a lithium ion, as negative electrode active material and is formed on at least single surface of a strip-shaped negative electrode collector. INDEPENDENT CLAIMS are included for the following:    (1) positive electrode active material; and    (2) positive electrode mix, which has positive electrode active material containing lithium-transition metal composite oxide of spinel structure, and electroconductive agent.