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, aggregate existing in the mixed powder of particles is dispersed. Specifically, the dispersion is performed at the high dispersing condition by an ejector, a pipe or the like. Thereafter, the particles having different characteristics are separated by the electrostatic separator or the magnetic separator.