A network boot system including one or more client terminals, a DHCP (Dynamic Host Configuration Protocol) server, a PXE (Preboot Execution Environment) server, a TFTP (Trivial File Transfer Protocol) server, a database administration server, one or more storage devices, and an authentification server (such as a Radius server) connected to each other via a TCP/IP (Transmission Control Protocol)/Internet Protocol) network. A plurality of LU provided in the storage devices as separated into a system area LU and a user area LU prepared per user.