The purpose of this study is to develop the new cuff improving the accuracy of blood pressure measurement, and to evaluate the performance of the developed system. We added a small bladder to the normal cuff which is called the double bladder system. The developed system for blood pressure measurement was based on the oscillometric method using a double bladder. This system was developed in order to reduce the oscillation noise and to amplify the signal of pure blood pressure An oscillometric signal database based on the developed system were evaluated following the standard ANSI/AAMI/SP10-1992. The correlation coefficients between cuff of double bladder and normal cuff were 0.98 for systolic and 0.94 for diastolic. Mean differences and the standard deviations between average blood pressure of mercury sphygmomanometer and automated sphygmomanometer were -0.7mmHg and 4.9mmHg for systolic, and -1.4mmHg and 5.4mmHg for diatolic, respectively. We conclude that the proposed double bladder based cuff system improves the accuracy of the oscillometric blood pressure measurement. The developed system reduces the error range about $44~62\%$ for systolic and about $6~21\%$ for diastolic compared to the recently developed commercially available sphygmomanometers.