A lithium ion secondary battery 10 includes at least one cell obtained by laminating a positive electrode 1, an electrolyte layer 2, and a negative electrode 3 in this order. The electrolyte layer 2 contains a fluoride. The negative electrode 3 has a negative electrode active material layer containing a silicon compound. At least one of the negative electrodes 3 has a mass ratio of fluorine/silicon (F/Si ratio) of 1.0 or less on a surface of the negative electrode active material layer.