PURPOSE: To improve the efficiency of access by executing the batch processing of cluster I/O operation applied plural uncontinuous pages as if the whole clusters are stored in one page.

CONSTITUTION: The titled system is provided with a cluster management list forming means 1 for forming a table including management information on a data base 4 for respective clusters and an I/O means 3 for rearranging the clusters applied to plural uncontinuous pages within a leading page including a master record for the cluster or within plural pages continued from the leading page and collectively inputting/outputting the clusters even if they are applied to plural pages. Even if the clusters are stored in uncontinuous pages, the whole clusters can be collectively outputted.