As the importance of human rights issues in supply chains grows, buyers are needed to understand their suppliers’ business environments. This study aims to elucidate the significance of developing external environmental management control systems through examining how buyer companies influence suppliers to approach to human rights issues voluntary and continuously. A multiple case study method was employed in this research （it can be also regarded as a （partial） single-case study method）. The case companies are Kirin H. Co., Ltd., recognised for its CSV initiatives, and Shionogi Co., Ltd., a prominent Japanese pharmaceutical company. Cooper and Yoshikawa （1994） served as the analytical framework for this study （TYK Model）. Cooper and Yoshikawa （1994） illustrate the mechanism achieving the goal congruence by realising business strategy of total supply chain throgh ensuring fulfil their respective roles （buyers, primary suppliers, and secondary suppliers）. Analysis of the two cases using this framework demonstrates that the realisation of the buyer’s sustainability strategy depends on each actor fulfil their assigned role. We also identified two forms of external environmental management control: a method in which the buyer indirectly influences the buyer company through evaluations using the buyer’s own evaluation system （Kirin H. and Shionogi）, and a method in which the buyer company directly influences to introduce environmental management control systems within their suppliers （Shionogi）. In short, expanding environmental management control externally to the company involves two key aspects: ‘extending’ the scope of the control systems to external entities （common to each company’s case）, and ‘expanded reproduction’ the structure （e.g., Daiwa House: Ando 2026） and the mechanisms （e.g., Shionogi） of the control systems within external organisations.
