Electrode active material of the invention is mainly an amorphous transition metal complex represented by AxMPyOz (where x and y are values which independently satisfy 0≦x≦2 and 0≦y≦2, respectively, and z=(x+5y+valence of M)/2 to satisfy stoichiometry; also, A is an alkali metal and M is a metal element selected from transition metals), and has a peak near 220 cm−1 in Raman spectroscopy. Applying the electrode active material of the invention to a nonaqueous electrolyte secondary battery increases the capacity of the nonaqueous electrolyte secondary battery.