1. A data access method in an information system comprising a plurality of data utilization systems connected to networks N 1 and N 2, and a plurality of data provision systems connected to the network N 2, said method comprising steps of: a data utilization system P 1 transmitting a request for utilizing data in a data provision system D 2 to another data utilization system P 2 through said network N 1 ; said data utilization system P 2, upon receipt of said data utilization request, transmitting a processing execution request corresponding to said data utilization request to said data provision system D 2 through said network N 2 ; said data provision system D 2, upon receipt of said execution request, executing processing corresponding to said execution request and transmitting necessary data to another data provision system D 1 through said network N 2 ; and said data provision system D 1 receiving said data and storing the same.