The aim of this study is to prepare mucoadhesive chitosan microspheres for protein drug to deliver to intestine through oral administration. The thiolated Eudragit was synthesized by reaction between L-cysteine hydrochloride and Eudragit® L-100. About 8 mol-% of cysteine was introduced to the Eudragit-cysteine conjugate. The conjugate was used to coat bovine serum albumin (BSA)-loaded chitosan microspheres. The average particle sizes of BSA-loaded thiolated Eudragit-coated chitsoan microspheres (TECMs) were 4.06±0.74 .m and the uniform sizedistribution was shown. The in vitro release of BSA from BSA-loaded TECMs was pH-dependent. Our results indicated that thiolated Eudragit might be a good candidate as a coating material for oral delivery of protein drug owing to mucoadhesive and pH-sensitive properties.