PURPOSE: To make format converting work executable in parallel with on-line job processing so that one obstruction to no-break operation can be eliminated by providing a format management table and format conversion logic.

CONSTITUTION: 7The latest information about format display is stored on a format management table 7 against all kinds of formats belonging to a data base 4 and, when changing of a format is required, '1' is added to a relevant format display on the table 7. When the record of the kind of format updated in accordance with a retrieval request from an application program 1 is re trieved, the retrieved record is converted by using format conversion logic 8 and the converted record is given to the program 1. Therefore, the record format converting work can be performed in parallel with on-line job processing and one problem for no-break operation can be eliminated.