In this paper, the function factors contributing to ITA/EA functions in their organizations, are suggested. Also the reasons to the construction of IT governance system and their effects on the their organizations are discussed and the relationships are verified by empirical model. From the survey, the data of the 227 respondents were collected and regression analysis was performed for validating the research model. ITA/EA functions consist of the IT infrastructure systemization, ITA/EA business process support, IT investment efficiency factors. And the factors of IT resource and performance management, IT process management, IT service management are included to IT governance. The main analysis results described significantly are shows as follows. At first, IT resource and performance management factor is effected by the ITA/EA business process support factor and IT investment efficiency factor. In similarly, IT service management factor is also affected by the factors such as ITA/EA business process support, IT investment efficiency, and IT infrastructure systemization. In additional analysis, IT investment efficiency factor in official sectors, ITA/EA business process support factor in private sectors respectively are described as the significant factors on the IT governance.