A negative electrode active material which is a negative electrode active material containing particles of a negative electrode active material, wherein the particles of the negative electrode active material contain particles of a silicon compound which contain a silicon compound (SiOx: 0.5≤x≤1.6), the particles of the negative electrode active material contain lithium, and the particles of the negative electrode active material have a peak in the range of 2θ=31.8±0.5° measured by X-ray diffraction spectrum using Kα line of Cu. According to this constitution, it is provided a negative electrode active material capable of improving cycle characteristics and initial charge and discharge characteristics when it is used as a negative electrode active material of a lithium ion secondary battery.