A negative electrode active material, wherein the negative electrode active material is a negative electrode active material including negative electrode active material particles; the negative electrode active material particles include silicon compound particles including a silicon compound (SiOx: 0.5≤x≤1.6); the silicon compound particles include at least any one kind or more kinds of Li2SiO3 and Li4SiO4; the negative electrode active material particles have a loose bulk density BD of 0.5 g/cm3 or more and 0.9 g/cm3 or less, a tapped bulk density TD of 0.7 g/cm3 or more and 1.2 g/cm3 or less, and a compression degree of 25% or less, the compression degree being defined by (TD−BD)/TD. Therefore, the negative electrode active material which is capable of improving the initial charge and discharge characteristics as well as the cycle characteristics upon using it as the negative electrode active material of a secondary battery is provided.