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PROBLEM TO BE SOLVED : To provide a lithium ion secondary battery improved in cycle characteristics than conventional one in the case of repetition of intermittent cycles. SOLUTION : In the lithium ion secondary battery, a positive electrode includes active material particles made of a lithium compound oxide and the lithium compound oxide is expressed by a general formula (1) : LixM1-yLyO2 (0.85≤x≤1.25, 0≤y≤0.50, the element M is one kind selected from a group made of Ni and Co, the element L is at least one kind selected from a group made of an alkaline earth element, transition metal element, rare earth element, a group IIIb element and a group IV element), the surface layer part of the active material particles includes at least one kind of element Le selected from a group made of Al, Mn, Ti, Mg, Zr, Nb, Mo, W and Y, and the active material particles are surface treated by a coupling agent. COPYRIGHT : (C)2007, JPO&INPIT