The firmware update apparatus is configured so that data required for update is accessible from both of normal firmware and emergency firmware and is provided with a section which sets the next-time boot destination to the emergency firmware during update, a section which saves a file before update into an area originally occupied by an update file, a section which inspects that a file required for booting the normal firmware is not broken or confirms that activation is actually possible from a virtualized environment, during activation of the emergency firmware, a section which restores the state before update by the saved files before update and a new update procedure automatically generated by reversing the contents of operations of the update procedure, and a section which, for each update file, describes a necessary reactivation target in the update procedure.