A to-be-treated body, which contains raw material particles 5 of a substance and with which a solvent 4 of a to-be-treated liquid 2 is made solid, is used, and a laser light source 10, which supplies a laser light of a predetermined wavelength to a treatment chamber 3 that contains the to-be-treated body, is provided to arrange a production apparatus 1A. The laser light from the laser light source 10 is illuminated onto the to-be-treated body to microparticulate the substance in solvent 4. As the to-be-treated body of solid form, a solidified body 6, with which water 4 is solidified by a cooling device 50 and the solidified state is maintained by a thermally insulating layer 30, may be used. Or, as the to-be-treated body, a gel body, with which the solvent is gelled, may be used. The substance can thereby microparticulated efficiently by photo-pulverization.