1. A configuration information management apparatus comprising: a data management unit that stores therein configuration items each having attribute items described according to different schemas; a dictionary candidate retrieval unit that specifies the attribute items of the schemas in the same configuration item for each of the configuration items stored in the data management unit based on a correspondence between the attribute items of the different schemas and retrieves, as a dictionary candidate, a combination of attribute names corresponding to the same attribute value among the attribute items of the schemas from the data management unit; a dictionary generation unit that generates dictionary information defining synonymity between the attribute names of the attribute items described according to the different schemas based on the dictionary candidate retrieved by the dictionary candidate retrieval unit; and a dictionary management unit that stores therein the dictionary information generated by the dictionary generation unit.