We have synthesized methoxy poly (ethylene glycol)-grafted-chitosan (ChitoPEG) copolymer to prepare RA-encapsulated polymeric micelle. RA-encapsulated polymeric micelle of ChitoPEG copolymer has 100-500 nm in their particle size and spherical shape in obwervations by TEM. In 1H NMR study specific peaks of RA and chitosan as a drug carrying innercore was disappeared at D2O and only specific peak of MPEG was shown, while specific peaks both of MPEG, RA, and chitosan were appeared at DMSO. indicating that RA/ChitoPEG ion complexes composed of polymeric micelle with core-shell structure and free drug does not exist on the polymeric micelles formulations.