To automatically interchange data between data bases and reduce complicated operation processes by a human by making a data transfer destination system perform processes for the data base of the data transfer destination system according to a 2nd journal transferred from a journal transmitting means.

A data transfer source system 10 is provided with a conversion rule table 14 in which an interchange rule is generated and stored, a journal converting means 15 which converts a journal into the 2nd journal matching the data base format of the transfer destination system 20, and a journal transmitting means 16 which transfers the 2nd journal obtained by the journal converting means 15 to the data transfer destination system 20. The data transfer destination system 20 is a data interchanging mechanism which uses the journal for processing the data base of the data transfer destination system 20 according to the 2nd journal transferred from the journal transmitting means 16.