The present invention provides a method for producing nanometer-size spherical particles. The method includes a first step for producing intermediate spherical particles. The intermediate spherical particles include a polycrystalline or single-crystalline region, having a particle size of 1 to 300 μm. The method of the present invention further includes a second step for producing final spherical particles. The second step uses a swirling plasma gas flow having the central axis thereof, the central axis running through an area between an anode and a cathode of a plasma generator. The intermediate spherical particles are discharged along the axis to subject the intermediate spherical particles to a plasma atmosphere of the area to form the final spherical particles.