The purpose of the invention is to provide a non-aqueous electrolyte secondary battery having a large battery capacity and excellent charge and discharge cycle characteristics. The non-aqueous electrolyte secondary battery comprises a negative electrode containing a particulate negative electrode active material (33), a positive electrode, and a non-aqueous electrolyte. The particulate negative electrode active material (33) includes a plurality of two-phase regions (34) in a particle, said two-phase regions (34) each including a first phase (A) containing silicon and a second phase (B) containing silicon oxide formed on the periphery of the first phase. In the particulate negative electrode active material (33), the ratio of the intensity of a Raman spectrum obtained by a Raman spectroscopy at a wavelength of 480 cm-1 with respect to the intensity thereof at a wavelength of 510 cm-1 is 0.1 or less, and the ratio of the intensity of an x-ray diffraction pattern obtained by an x-ray diffraction measurement at 2[theta] = 21.6 with respect to the intensity thereof at 2[theta] = 28.4 is 0.1 or less.