1. A data transforming method for a data transforming system installed between first and second information processing systems, said first information processing system transmitting request data in accordance with a first business protocol and said second information processing system returning response data to the request data in accordance with a second business protocol, said first business protocol being constituted of a format of transaction data containing data item information and data defined by the data item information and a transmission/reception procedure of transmitting request data and returning response data to the request data, the data transforming method comprising steps of: receiving request data containing a plurality of requests transmitted from said first information processing system in accordance with said first business protocol; dividing and transforming said transmitted request data into a plurality of request data sets each containing an independent request having a format defined by said second business protocol, and transmitting said plurality of request data sets transformed to said second information processing system in accordance with said second business protocol; receiving a plurality of response data sets each returned from said second information processing system, corresponding to each of said plurality of requests and having a format defined by said second business protocol; and collecting said plurality of response data sets, transforming said plurality of response data sets into a plurality of response data sets corresponding to the plurality of requests and having a format defined by said first business protocol, and transmitting said plurality of response data sets transformed to said first information processing system in accordance with said first business protocol.