1. A semantic-based searching apparatus comprising: a storage unit configured to store: an associative search structure previously defined to obtain a final search object in response to an input search query, and semantic metadata which is stored in conformity with a semantic index configuration that includes a feature metadata index including feature metadata used to identify a specific object, a semantic entity metadata index to indicate semantic entities corresponding to the feature metadata, and a semantic relation metadata index to indicate a relation between the semantic entities; and a control unit configured to generate a search result corresponding to the final search object in response to the input search query using the semantic metadata and the associative search structure.