As the amount of IT investment and the complexity of information systems in public agencies have been increased, efficient and structured management of IT systems is more emphasized. For the Korean government. ITA (Information Technology Architecture) is one of the core parts of the e-Government initiative. Also introducing and managing ITA in organizations is mandated by law in Korea. The objective of the paper is to study whether using ITA in public agencies is related with their IT capability and IT performance or not. A questionnaire had been designed for the purpose, and a survey had been performed on Korean public agencies. The survey results show that using ITA has influence on relation and technology capability. However, ITA does not influence on human capability and IT performance. The reason why using ITA is linked to relation and technology capability is that ITA includes relationship between both business and technology. Also ITA provides a technical reference model (TRM) and standard profile (SP), so it has influence on technology capability.