PURPOSE: To produce a superfine powder by introducing a gas close to the bottom of a rotating vessel contg. a fine powder, discharging the fine powder along with the gas as an aerosol and supplying the aerosol into plasma.

CONSTITUTION: A fine powder 5 is charged into the cassette 3 of an aerosol producing device 1, a carrier gas or a mixture of the carrier gas and gaseous reactant is introduced from an inlet 6 close to the bottom of the cassette 3, and the cassette 3 is rotated. Consequently, the fine powder 5 is blown up from the bottom by the gas and suspended to form an aerosol 16 in which the fine powder is dispersed, and the aerosol is supplied into the plasma 21 in a high-frequency hot plasma producer 19 through a transport pipe 9 and a supply pipe 20. Since the fine powder is supplied into the plasma in uniform concn., a superfine powder of a single crystal structure with the width of distribution reduced and having a desired composition is obtained.