Many biological processes are usually coupled to the formation of protein complexes. The yeast two-hybrid system is a powerful tool for analyzing protein-protein interactions. Different patterns of protein modifications, such as glycosylation, phosphorylation, and acetylation, may affect the ability of proteins to interact. In this study, we developed the two-hybrid system that can be used in insect cells. To validate the insect two-hybrid (I2H) system, we analyzed and confirmed the known oligomer or dimer formation of silkworm Rad51 or RPA2-RPA3, respectively. The results established the feasibility of the I2H system for efficient analysis of protein interaction under conditions that closely reflect the normal physiological environment.