In this thesis, an expert system developed with an ontology-based approach to detect Service Level Agreement (SLA) violations is presented. Ontologies represent explicit formal specifications of the concepts in a particular domain and the relationships among them. Expert systems, however, are frequently employed with ontologies because of their reasoning capabilities. The widespread use of SLAs in various areas complicates SLA management and in particular the detection of violations. Although it is necessary to automatically detect SLA violations, developing a different solution for each domain is quite costly. In SLAs of multiple domains, the concepts were examined, and many common concepts have been identified. Identifying familiar concepts in different SLA areas has allowed us to acquire the idea of creating a generic SLA ontology. After generic SLA ontology was created, an expert system was developed using this ontology. The developed expert system is designed to detect SLA violations, check constraints, and make inferences. The developed system has been tested on the SLA data of the telecommunication domain. The results show that the proposed system can correctly detect SLA violations.