To prolong efficacy of porous fine particles for sustained release containing or absorbing a substance such as pigment, perfume, agrochemical or medicine because conventionally adopted porous fine particles cannot sustain the efficacy for a long time.
This invention provides the porous fine particles with sustained release obtained by supporting the contained substance obtained by covering an objective material for supporting with a permeable material. The method for the production comprises a method for supporting the contained substance obtained by covering the objective material with the permeable material to initial porous fine particles by soaking the initial porous fine particles in a solution obtained by dissolving the objective material for supporting and the permeable material to a solvent and then removing the solvent or a method for soaking the initial porous fine particles in a solution obtained by dissolving the objective material for supporting to a solvent and then removing the solvent and again soaking the particles to a solution obtained by dissolving the permeable material in a solvent and then removing the solvent.
NAKAYAMA TAKUSHI