The invention provides a lithium ion secondary battery which exhibits excellent output characteristics and in which decline in the power characteristics is suppressed for a long period of time even after charge-discharge cycling. The lithium ion secondary battery includes a positive electrode, a negative electrode and a nonaqueous electrolyte solution. The positive electrode has a maximum achievable potential of 4.5 V or more versus metallic lithium. The nonaqueous electrolyte solution includes (A) a nonfluorinated cyclic carbonate, (B) a fluorinated cyclic carbonate, and (C) a fluorinated acyclic carbonate. The nonfluorinated cyclic carbonate (A) accounts for more than 10% by volume of (A), (B) and (C) combined.