Abstract: Herein disclosed is a backup system capable of easily performing backup and/or restore operations of an entire hard disk (HD) inclusive of a system region regardless of a type of an OS installed thereon in a computer such as a personal computer (PC). The backup system is suitable for backing up a hard disk of a computer which is connected to a server via a network, and characterized in that the server comprises: a boot OS creation section adapted to create a boot OS for the computer; a backup section adapted to store as a file the content of the hard disk in the computer into a designated backup destination; a management information database adapted to store therein management information of the computer; and a kernel image adapted to serve for the creation of the boot OS, as result of which it is possible to perform the backup and/or restore operations of the hard disk in the computer with easy manipulation by executing backup and restore functions from the boot OS.