Active Material

An active material comprising silicon and a compound represented by MxSiy, where x and y satisfy 0.1≤x/y≤7.0, and M represents one or more metalloid elements other than Si and metal elements, wherein the content of Si elements is more than 50 wt %, the content of M is less than 38 wt %, and the content of oxygen elements is less than 30 wt %; D50 and Dmax are less than 4.0 μm and less than 25 μm, respectively; and in an X-ray diffraction pattern measured by an X-ray diffractometer (XRD) using CuKα1 rays, the full width at half maximum of a peak A appearing at 2θ=28.42°±1.25° is 0.25° or more, and when the peak intensity of a peak B belonging to the compound is defined as IB and the peak intensity of the peak A is defined as IA, the ratio (IA/IB) of the IA to the IB is less than 1.