The unit of competition is not a single firm any more but group of firms. They make a supply chain and compete with other chains. In this study we investigate success factors of supply chains from the supplying firms perspective. We consider various success factors such as commitmet trust communication confilct re-solving techniques vendor selection process and incentive systems. A set of hypotheses is tested based on the data collected from the electronics and automobile part manufacturers. Samples are divided by the length of the relationship between the vendor and assembler. joint problem solving under the long-term relationship plays an important role for the success of the supply chain. The findings offer insight into how to better manage the sup-ply chains.