The inventive negative electrode active material for a non-aqueous electrolyte secondary battery contains negative electrode active material particles which include silicon compound (SiOx: 0.5≤x≤1.6) particles. The negative electrode active material particles are at least partially coated with a carbon material, contain one or more selected from Li2SiO3 and Li2Si2O5, and satisfy Ib/Ia≤4.8 and Ic/Ia≤6.0 in an X-ray diffraction measurement using a Cu-Kα line. Ia represents an intensity of a peak around 2θ=28.4° attributable to Si obtained by the X-ray diffraction. Ib represents a peak intensity of a peak attributable to Li2SiO3 obtained by the X-ray diffraction. Ic represents a peak intensity of a peak attributable to Li2Si2O5 obtained by the X-ray diffraction. Thus, the present invention provides a negative electrode active material for a non-aqueous electrolyte secondary battery, which is stable over a long period even in an aqueous slurry and enables high capacity, favorable cycle characteristics and first-time efficiency.