Manufacturing flexibility has strategic position in improving competitive advantage as a mechanism that responses environmental uncertainty. Thus this study aims at recognizing strategic meaning of manufacturing flexibility in enhancing the competitive advantage and measuring manufacturing flexibility and ultimately analyzing the effects of IT use on the manufacturing flexibility. Consequently we proved that IT use have an effect on manufacturing flexibility and manufacturing flexibility has an effect on competitive advantage in this study The results of this study are as follows. First, information acquisition and decision support by IT use has a significant effect on enhancing the manufacturing flexibility and manufacturing flexibility has a significant effect on improving the competitive advantage. Theses results are also means that IT use to support AMT usage is more important than AMT itself in the achieving manufacturing flexibility