To realize securing of the traceability and reduction of the number of processes for creating a new version application by executing the validity more correctly and efficiently in confirming work when a file and the like modified/added by a program developer is used as a master program in structural management in application development on a large scale.

A means enabling the program developer to confirm the validity of the file or the like modified/added with respect to the master program on the basis of bug management information or version information is provided. Also, a means for confirming omission of an item to be modified when a plurality of items of an identical file are modified, and a data base searching for files to be used for confirmation easily are provided.