The rapid development of IT and the large-scale investment of IT motivate the public agencies to find the ways of effective IT management. Even though the public agencies adopt Enterprise Architecture (EA) as the new alternative for effective IT management, EA practices are still insufficient in the area of utilization and management after the adoption. Therefore, this research aims to identify the influencing factors for improving EA maturity level in terms of the long-term business activities such as establishment, management and utilization. Also, this research empirically identifies the influencing factors on the adoption and operation of EA in the public agencies, and clarifies how such factors impact on EA maturity level.