The global recession circumstances, cloud computing has emerged as a new paradigm in the business IT sector. This paper explores the analysis of cloud service adoption Intension of Korean firms. Especially, we focus on Infrastructure as a Service (IaaS) among cloud services and apply TAM (Technology Acceptance Model) and VAM (Value-based Adoption Model) to analyze cloud service adoption intension The proposed exploratory model tests a number of hypotheses to understand the importance factors of IaaS adoption intension with TAM and VAM included additional cloud service characteristics such as scalability, agility, security, efficiency and reliability. Eventually, the findings of this study can not only help company users gain insights into IaaS adoption, but also help cloud service providers to develop their service effectively and improve marketing strategy in B2B cloud service market.