The purpose of this qualitative research is to analyze the scope of localization of supplier management in Western Digital (Thailand) which is a Hard Disk Drive manufacturer. The authors have adopted the case research method and gathered the information by conduction in-depth multiple interviews with 15 employees at various levels of Western Digital and 16 employees of 7 suppliers. It was found that Western Digital implements localization of supplier management in 3 areas: localization of material; working with local supplier including supplier selection, supplier relationship and use of local supplier network; and localization of knowledge magement for manufacturing process adaptation, product adaption and new production development.