In studies on buyer–supplier relationships, interdependence is a commonly used keyword; however, its definition and measurement items have not received much attention. By reviewing the literature, this study found two streams in studies associated with interdependence, with each stream having certain commonalities in its measurement items. In the power-related context based on Resource Dependence Theory by (1) Pfeffer and Salancik (1978), it tends to use the percentage of sales accounted for by the trading partner, the substitutability of trading partners, and the switching cost, whereas in the task-related context based on (2) Thompson’s (1967) technology, dependence on the traded input and output is often used as measurement items for interdependence. In fact, both logics are implemented in Toyota Motor Corporation’s supplier management, using multiple suppliers to avoid resource dependence while some parts are determined by technology.