A secondary battery includes a cathode, an anode, and an electrolyte. The anode includes an anode active material containing silicon, boron, carbon, and one or more of metal elements selected from the group consisting of cobalt, titanium and iron. In the anode active material, a boron content is from 4.9 mass % to 19.8 mass % both inclusive, a carbon content is from 4.9 mass % to 19.8 mass % both inclusive, a total of the boron content and the carbon content is from 9.8 mass % to 29.8 mass % both inclusive, a ratio of a silicon content to the total of the silicon content and a content of the metal element is from 70 mass % to 95 mass % both inclusive. A reaction phase whose half-width of a diffraction peak obtained by X-ray diffraction is 1 degree or more is included and the anode active material is capable of reacting with an electrode reactant.