In this study, we synthesized an amphiphilic polyhedral oligomeric silsesquioxane (POSS) having controlled numbers of hydrophilic and fluorescent hydrophobic groups. (seven and one, respectively) by the successive reactions of a starting compound, octa(3-aminopropyl)-POSS, with - gluconolactone and with dansyl chloride under appropriate conditions. The product formed fluorescent nanoparticles with relatively well-defined morphology in water by self-aggregation, which was confirmed by SEM, DLS, and fluorescence measurements.