To provide an innovative supercritical fine particle production apparatus with improved solute solubility which can quickly and reliably dissolve a solute in a supercritical fluid although having simplified structure of a reactor and which does not cause precipitation of the solute in the reactor.

This apparatus is for obtaining a granule G by increasing the pressure and the temperature of a liquid by a pump 5 and a preheater 6 for producing a supercritical fluid F; at the same time, obtaining a supercritical fluid S, in which a solute M is dissolved, by dissolving the solute M in the supercritical fluid F in a reactor 1; and rapidly expanding the supercritical fluid S in which the solute is dissolved by spraying the fluid S to a collector by a nozzle 14. In the apparatus, the reactor 1 is provided with a solute loading chamber 10 and a dissolution pipeline 11, and since the supercritical fluid F passing through the solute loading chamber 10 flows into the dissolution pipeline 11 while being accompanied with the solute M set in the solute loading chamber 10, the solute M is dispersed in the supercritical fluid F and thus dissolution of the solute M in the supercritical fluid F can be carried out quickly.