A first code-format converting unit extracts data from database management apparatuses that manage databases having same contents, and converts a code format of the extracted data into a common code format. A mismatch-resolving-data generating unit generates mismatch-resolving data for resolving a data mismatch between the database management apparatuses, from the data with the code format converted. A second code-format converting unit converts a code format of the generated mismatch-resolving data into a code format corresponding to the databases. A database updating unit reflects the mismatch-resolving data with the code format converted to the databases.