To provide a method for improving the fact that a separation efficiency is extremely insufficient and does not reach to a practical level regarding many particles in separation of particles by an electrostatic separator and a magnetic separator conventionally.

In the electrostatic separator and the magnetic separator, before the particles are charged with a charge or magnetism in order to separate a mixed powder of particles having different characteristics, a fine powder having a spherical corresponding diameter of 10 μm or less is classified by a classifier so as to become 15 mass% or less. After the classification, prior to the electrostatic separation or the magnetic separation, an operation for dispersing of the mixed powder of the particles may be performed.