To prolong the shelf-life of chicken breast meat, samples were treated with gel packs containing slow-released chlorine dioxide (ClO2) gas at 7~15 ppm for eight days at 4℃. The microbial, physicochemical properties and sensory evaluation of the treated samples were investigated. The total number of bacteria in the control increased during storage and showed 6.78 log CFU/g on the 8th day of storage, but ClO2 gas treatments showed 6.24~6.58 log CFU/g at the same time. The initial pH of chicken breast meat was 6.00 and gradually increased during storage. And ClO2 gas treatments did not show any significant difference from the control during storage period, but maintained a generally lower pH than that of the control. The lightness, redness, and yellowness during storage were not significantly different between the control and the 7~10 ppm ClO2 gas treatments. However, as the storage period was increased, the redness of 15 ppm ClO2 gas treatment was reduced. The cooking loss and shear force were not different between the control and ClO2 gas treatments during the storage period. Volatile basic nitrogen (VBN) increased in the control from the 6th day of storage and 23.80 mg% in the 8th day of storage. However, VBN of ClO2 treatments showed lower than that of the control. In the change of sensory evaluation during storage, 10 ppm ClO2 treatment showed the highest preference in odor, appearance and overall acceptance during storage period.