PURPOSE: To simplify the interface of an application program.

CONSTITUTION: When an application program A2 utilizes a transaction monitor A4 while executing a transaction at a computer A1, it is stored in a storage means A41 by the relevant transaction monitor A4. When ending the transaction by the application program A2, the end request of the transaction is outputted to a data base management system A3. Then, it is inquired from a state managing part A30 to the transaction monitor A4 whether the transaction monitor is utilized by the application program A2 or not. The update processing of a data base A5 of the computer A1 is performed by a retrieval/update control part A32. Then, the update processing is performed while synchronizing respective data bases A5 and B5 of plural computers A1 and B1 through the transaction monitor A4 with the transaction control part A31.