This paper identifies the determinants of adoption and diffusion of e-government services, and examines the causal relationship among the variables of adoption behavior. The main findings, based upon survey responses from service users, are as follows: first, both the value of service and the socially influencing factor have the positive effect to the intention of utilizing services. Second, the socially influencing factor has the indirect effect to the intention of utilizing services, because it positively affects the value of service. The interaction factors, however, do not directly affect the intention of utilizing services. These interaction factors indirectly affect the intention of utilizing services through the path which increases the value of service, and its effect is larger than the socially influencing factor.