The present invention provides a flexible ontology data import/export method and apparatus. The ontology data import apparatus comprises: an ontology data format analyzer for analyzing a format of input ontology data, and performing format determination by utilizing an ontology format database which stores formats of those successfully imported ontologies if it is a private unknown format; and an unknown format data importer for separating and importing the data into an ontology database which stores ontologies, in accordance with a result of the format determination by the ontology data format analyzer. Further, the ontology data export apparatus comprises a keyword-based and query-language-combined ontology exporter and an ontology data export format analyzer, and the keyword-based and query-language-combined ontology exporter outputs a query result returned from the ontology database in accordance with the export format returned from the ontology data export format analyzer.