A lithium ion secondary battery includes a positive electrode having a positive electrode active material layer on a current collector, a negative electrode having a negative electrode active material layer on a current collector, and a separator disposed between the positive electrode and the negative electrode and impregnated with a non-aqueous electrolyte solution. The positive electrode active material layer contains a positive electrode active material and a binder, the negative electrode active material layer contains a negative electrode active material and a binder, the binder of the negative electrode active material layer contains a copolymer of vinyl alcohol and an alkali metal neutralized product of ethylenically unsaturated carboxylic acid, and the separator includes a polymeric base material containing an inorganic compound or includes a polymer having a melting point or glass transition temperature of 140° C. or higher.