We present in this paper the methodology for automatic generation of OWL-S service model ontology along with the results and issues. First, we extract information related to atomic services and their properties such as IOPE from the UML class diagram, and retrieve information related to the composition of services from the UML state-chart diagram. Then, the XSLT applications utilize the acquired information to generate the OWL-S service model ontology through the predefined mappings between OWL-S constructs for composite services and UML state-chart primitives. For the justification of generated service ontology, several validation checks are performed. Our service ontology generation method is general and fully automatic, as well as effective, in that it is achieved in an environment familiar to developers, and information needed to generate service ontology is provided necessarily during service development. It is also noticeable to facilitate representing the condition with GUI rather than a complex language such as OCL.