This study examined virtual organizations that have developed in response to changes in technology and environment, and explains the factors that can influence virtual organizations. Virtual organizations, whose purpose is to enhance organizational efficiency through the linkage of core technologies, demonstrate that trust among participating members within the virtual organization serves as a critical variable, and this study attempts to verify the factors that affect such trust. This study measured trust in terms of uncertainty and opportunism, and proposes knowledge specificity, knowledge connectivity, emotional compatibility, and openness of communication as factors influencing trust. A survey was conducted using mail and e-mail, and questionnaires were distributed to 595 transaction managers at firms forming various types of value chains that link core competencies—including firms engaged in inter-firm cooperation through hub sites utilizing the Internet, and firms in alliances for production and sales—yielding 115 valid responses. Path analysis using LISREL 8.12 was employed to test the research model. The results show that all factors except knowledge connectivity had a positive effect on trust as measured by uncertainty and opportunism.