||We synthesized methoxy poly(ethylene glycol)/poly(D,L-lactide) block copolymer. These core-shell polymeric nanosphers consisted of hydrophobic inner core and hydrophilic outer shell form micelles in selective solvent. Using this result, we prepared 5-Fluorouracil loaded block copolymeric nanospheres composed of methoxy poly(ethylene glycol)/poly(D,L-lactide) as anticancer drug carrier. In this study, we observed morphology change of amphiphilic block copolymeric nanospheres as drug release. Morphology observation used CLSM(Confocal Laser Scanning Microscopy).