在委外代工與採購的垂直交易結構中，供應商關係管理是廠商垂直整合策略中重要的決策。中心廠若能與提供關鍵要素的主要供應商維持緊密的合作關係，可發揮降低營運成本、聚焦組織核心能力之策略性效益，但若過度依賴特定的主要供應商，則可能導致供應商優勢的發生，並陷入非對稱依賴交易結構中所產生的套牢風險。實務中常見的管理問題，即在於如何維持交易關係的彈性，避免被特定供應商所套牢，並維持雙方的合作關係的穩定與發展。本研究從中心廠的角度，探討在與主要供應商間，高度互賴且非對稱的交易關係中，中心廠如何避免套牢風險，並提高與主要供應商之關係彈性。本研究以我國紡織業與資訊業為對象進行廠商問卷調查，採取結構方程模式分析250份樣本資料，驗證12項研究假說。實證結果支持8項研究假說：主要供應商移動彈性與中心廠認知合作績效呈負相關、中心廠移動彈性與中心廠認知合作績效呈正相關。關係深化、交易價值深化、關係探索等三項關係管理策略，與主要供應商移動彈性呈負相關；交易價值深化、結構探索兩項關係管理策略，與中心廠移動彈性呈正相關。本研究結合交易成本、資源依賴、廠商行為等理論觀點，以中心廠及主要供應商雙方的移動彈性作為組織間關係之決策準則，探討中心廠與其主要供應商之關係策略與管理作法，並進行理論意義與實務意涵之討論。

Managing the transaction relationships with the key supplier is a critical decision of strategy. The previous literature suggest that a firm can achieve the strategic benefits such as reducing operation cost and focusing on organizational core competence through outsourcing, while maintaining a close cooperative relationship with the key supplier who provides essential key factors such as key components or key material. However, focal firm may also hold-up by the key supplier when it over-dependent on the opposite site. Therefore, the practical puzzle is how to maintain flexibility of relationships in vertical transactions as well as to avoid hold-up by specific key supplier and to extend the transaction stability with the key supplier. Standing the view of focal buyer, the study explores two related questions: (1) how to avoid hold-up problem in an asymmetric buyer-supplier transactions, and, in the ex post transaction, and (2) how to increase relational flexibility in highly interdependence situation. The dyadic transactions between focal firm and its key supplier are the units of our analysis to confer with the managerial mechanism of key supplier relationship. The study establishes an exploration-exploitation framework adopted by focal firm adapt to ex post asymmetric interorganizational relationships. Thus it has summarized two strategic mechanisms: (1) reducing key suppliers' mobility of flexibility through relational exploitation as well as exploration on transaction value and relationship for reinforcing interdependency in dyadic transactions, meanwhile, (2) increasing focal firms' mobility of flexibility through structural exploration as well as transaction value exploitation so as to diminish the dependency on the key supplier and heighten alternatives to cooperate with. Using structure equation modeling approach, research hypotheses are tested on a sample of 250 focal firms established in Taiwan. We found the positive relationships between focal firms' mobility of flexibility and cooperative performance perceived by focal firm, and, the negative relationships between key suppliers' mobility of flexibility and cooperative performance perceived by focal firm. Empirical results confirmed the negative relationships between key suppliers' mobility of flexibility and focal firm's exploitation in relationship and transaction value as well as relationship exploration. The positive relationships between focal firms' mobility of flexibility as well as structural exploration and transactional exploitation were also supported. The study develop a theoretical extension based on the transaction cost theory, resource dependence theory, and the behavioral theory of firm. We also address dyadic mobility of flexibility as the decision criterion for balancing exploration and exploitation in the interorganizational relationship. These findings provide theoretical and managerial implications for vertical coordination in supplier relationship management in particular.