In this paper, we design and implement a Web-based Internet/Intranet service management system which can support Quality of Service (QoS) contracted by users and service providers, using Service Level Agreement (SLA) concept. We have analyzed the requirements and management information for Internet/Intranet service management. Based on this analysis, we have defined the suitable QoS parameters for the management of Internet/Intranet services, and developed new WWW service Management Information Bases (MIBs) for QoS management by extending the existing IETF's MIBs. The support of QoS management is done by incorporating the SLA concept, which is measured, monitored and controlled systematically in a multi-domain environment. Finally, we have built a prototype system, and evaluated its performance. The prototype system utilizes Java and CORBA technologies, so that various benefits of these technologies such as platform independence and scalability can be obtained.