A software update management apparatus includes a migration pattern table generation unit for reading a pre-migration environment table and a post-migration environment table and judging a migration content between before and after the update, for each function of a target disk node, and for reading a migration pattern determination table and determining a migration pattern to be applied to the target disk node based on the migration content and the migration pattern determination table. The software update management apparatus also has an update unit for reading the post-migration environment table, issuing an instruction to the target disk node according to the migration pattern determined by the migration pattern table generation unit, and updating software which executes each function of the target disk node.