The storage system of the present invention reflects the intentions of the host device in data migration carried out by a storage device. The host manager registers the host-side data migration policy in advance in the operation management server. When the storage device initiates the data migration, the management server compares the storage-side data migration policy and the host-side data migration policy, and when the polices match, the storage device is permitted to carry out the data migration. When the policies do not match, the management server prohibits the storage device from carrying out the data migration. The management server counts the number of times that the policies do not match, and generates and sends a report to the managers in order to draw the attention of the host manager and the storage manager.