Disclosed is an all-solid-state lithium ion secondary battery excellent in cycle characteristics. The battery may be an all-solid-state lithium ion secondary battery, wherein an anode comprises anode active material particles, an electroconductive material and a solid electrolyte; wherein the anode active material particles comprise at least one active material selected from the group consisting of elemental silicon and SiO; and wherein, for the anode active material particles, a value A obtained by the following formula (1) is 6.1 or more and 54.8 or less: A=SBET×dmed×D  Formula (1) where SBET is a BET specific surface area (m2/g) of the anode active material particles; dmed is a median diameter D50 (μm) of the anode active material particles; and D is a density (g/cm3) of the anode active material particles.