1. A configuration information management apparatus virtually federating configuration information scattered in operation management middlewares, the configuration information management apparatus comprising: a data management unit that stores therein configuration items each having attribute items each including an attribute name and an attribute value described according to different schemas, a same configuration item being described by different attribute names according to the schemas and a same attribute value being associated with different attribute names of the different schemas corresponding to the same configuration item; a dictionary candidate retrieval unit that refers to correspondence relation comparing the attribute items of a first schema with the attribute items of a second schema in the same configuration item for each of the configuration items stored in the data management unit, specifies an attribute item of the first schema and an attribute item of the second schema and, when retrieving the attribute name corresponding to the same attribute value between the specified attribute item of the first schema and the specified attribute item of the second schema, retrieves, as a dictionary candidate, a combination of the retrieved attribute name of the attribute item of the first schema and the retrieved attribute name of the attribute item of the second schema 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.