Amphilic terpolymers [consisting of 50 mol% of sodium sulfonate groups, 49.5% of lauryl (La) or cyclododecyl (Cd) groups, and 0.5 mol% of a moiety of azobenzene substituted with a La group (Abz-La) or with a Cd group (Abz-Cd)] were prepared. Reference copolymers [consisting of 99.5% of sodium sulfonate groups and 0.5 mol% of the Abz-La or Abz-Cd residue] were also prepared. In the terpolymers, the Abz-La and Abz-Cd residues were incorporated in the self-organized hydrophobic phases in aqueous solution, while in the reference copolymers, they are exposed to the aqueous phase. NMR data indicated that the motions of the azobenzene moieties in the terpolymers were highly restricted owing to the self-organization of the hydrophobic groups in aqueous solutions