Since the Semantic Web emerged, ontology has been widely used in web environment. Even ontologies belong to the same domain, they may contain same meaning different words, or different meaning same words according to their development background and the type of utilization. In order to share and reuse the ontologies, ontology mapping is required. This paper presents a ontology mapping method that consists of the initial process of multi-level mapping based on lexical information, and the second mapping process using the lexical results and structural similarity. Mapping performance was improved by additionally expanding structural information of blank nodes, which have no lexical information. Through experiments, our method achieved 86.38% in F1-measure.