In recent years, service discovery is one of the major technologies of home networks which head for a pervasive computing environment. However, existing service discovery techniques are difficult to understand of semantics of services, and they only provide exact service matching. To solve these problems, we have designed and developed ontology for semantic service discovery in home network environments. Ontology could enrich the amount of devices and services representations with semantics, which are helpful for discovering services. Our ontology expressed in DAML+OIL, describes device specifications and services that can be provided by various device in the home environments. Using the ontology, our semantic service discovery system can generate various types of service request messages, and reply the most appropriate result out of ontology reasoning process. To determine whether the developed ontology can be applied to service discovery systems, we have implemented a semantic service discovery system by extension of the existing Jini lookup service. We define additional components, such as reasoning engine for ontology reasoning, evaluator for dynamic value evaluation and matching manager for managing whole processes of service discovery. Also, we have evaluated our ontology with associated software environment according to some experiment scenarios, and have proved the usefulness of our ontology-based semantic service discovery system.