This study investigates why conflict of interest occurs in multi-bi ODA – a hybrid form of bilateral ODA and multilateral ODA – and focuses on the bilateral relations between donor countries and multilateral organizations for analysis. Significantly, donor countries and multilateral organizations can each have their respective interests due to the hybrid nature of multi-bi ODA, and consequently, the relationship of donor countries and multilateral organizations is not always cooperative and mutually beneficial in multi-bi ODA. In Particular, this study focuses on the reason why conflict arises in multibi ODA based on the Principal-Agent Model to analyze the conflict-based relationship of donor countries and multilateral organizations