LITHIUM ION SECONDARY BATTERY

In a herein disclosed lithium ion secondary battery, a positive electrode active material includes a lithium-transition metal complex oxide, containing Li, Ni, and Mn and being formed in a layered structure, and includes a covering part, a lithium-transition metal complex oxide has a Ni containing rate being equal to or more than 75 mol % with respect to the total of metal elements other than the Li and is a secondary particle consisted by a primary particle being aggregated, and the covering part contains a tungsten compound and/or a phosphorus compound. A negative electrode active material contains a carbon material and a Si containing material, and a containing ratio of a Si element in the negative electrode active material is equal to or more than 5 mass % and not more than 10 mass % when a total amount of the negative electrode active material is treated as 100 mass %.