The Semantic Web's success will depend on the implementation and use of Web Service becoming preeminent in Ecommerce, which will likely be agent-based in the future. On the Semantic Web, the agent can use the large amount of information available over the web, but this capability of the agent will allow it more subtle attacks. As the agent plays more mission critical roles within Web Service, the agent and supporting technologies need to be secure and reliable. Additionally, the agent has charge of different and various roles on the heterogeneous platforms over the Semantic Web. As a result of this, its requirement and qualification for access to information are dynamically changed according to the case. In order to make the agent secure and to support its work, in this paper, we will discuss the requirements for agent security on the Semantic Web and propose a method that the agent dynamically exchanges its authentication and authorization information using SAML. Finally, we wil...