According to one embodiment, a negative electrode active material for a non-aqueous electrolyte secondary battery cell includes a composite. The composite includes a carbonaceous material, a silicon oxide dispersed in the carbonaceous material, and a silicon dispersed in the silicon oxide. A half-value width of a diffraction peak of a Si (220) plane in powder X-ray diffraction measurement of the composite is in a range of 1.5° to 8.0°. A mean size of a silicon oxide phase is in a range of 50 nm to 1,000 nm. A value of (a standard deviation)/(the mean size) is equal to or less than 1.0 where the standard deviation of a size distribution of the silicon oxide phase is defined by (d84%−d16%)/2.