Now the knowledge source in natural language text are available in large quantities. There is an increasing need of knowledge representation, then it would require the knowledge processing on text automatically. The previous research has built on knowledge representation system of natural language text that is OWLizr. However, this study has not been able to handle the knowledge representation in concepts that describe a particular object. This paper developed a knowledge representation system in copula sentences containing concepts in Bahasa Indonesia. If the concept can be handled then the relationship between concepts with components of existing ontology can defined. This supports ontology engineering process that build domain ontology by enrich knowledge of the existing knowledge base. This system combine NLP (Natural Language Processing) techniques and OWL (Web Ontology Language) to model the knowledge contained in the copula sentence. The testing in this system is by unit testing and testing on collection of sentences which adapted from Wikipedia. The results of this research are system can represent knowledge in copula sentences containing concepts in Bahasa Indonesia. The system can generate output in OWL knowledge base that can share and reuse for other systems.