Amphiphilic copolymers of sodium 2-acrylamido-2-methylpropanesulfanate (AMPS) and dodecylmethacrylamide (DodMAAm) were synthesized. The ratio of the reduced viscosities of these copolymers in water and in 0.2 mol/L NaCl solution shows that these copolymers containing from 50 to 66 mol % of DodMAAm have a relatively small and constant hydrodynamic size. Viscometric and static light scattering measurements indicated that the copolymers shrinked and intermolecularly associated, forming interchain aggregates in water through hydrophobic interactions. These copolymers solubilize dl-alpha-tocopherol acetate, giving a transparent solution; but the solution became turbid in a month due to increasing intermolecular association To suppress this excess intermolecular association, polymers with four different crosslinking ratios were synthesized. The polymer of a crosslinking ratio of 0.5 mol % showed a strong solubilization property, resulting in transparent solution with an improved stability. The fluorescence spectra of pyrene in the polymer solution proved that these copolymers could form strong hydrophobic domains, which solubilize a hydrophobic compound, in less than 30 w/w % ethanol solution. These copolymers could have an excellent function of sustained release of perfume as a novel function.