The present invention provides a method for producing metal-supported carbon, which includes supporting metal microparticles on the surface of carbon black, by a liquid-phase reduction method, in a thin film fluid formed between processing surfaces arranged to be opposite to each other so as to be able to approach to and separate from each other, at least one of which rotates relative to the other, as well as a method for producing crystals comprising fullerene molecules and fullerene nanowhisker/nanofiber nanotubes, which includes uniformly stirring and mixing a solution containing a first solvent having fullerene dissolved therein, and a second solvent in which fullerene is less soluble than in the first solvent, in a thin film fluid formed between processing surfaces arranged to be opposite to each other so as to be able to approach to and separate from each other, at least one of which rotates relative to the other.