The present invention provides a storage subsystem capable of realizing efficient data migration and high access performance. During migration of data between storage subsystems, data migration methods are selected between a “PUSH” type and a “PULL” type method based on a data migration policy set in advance to perform data migration processes. An access characteristics of a file and a folder storing the file are determined based on a file access frequency or a final access date and time information in a migration source storage subsystem, and the migration order of a file group determined to have a high possibility of being accessed during data migration is changed between the “PUSH” type and the “PULL” type.