To provide a technique of allowing a terminal device to operate by downloading not only an application program but also an OS from a network without providing any special unit or equipment. A system includes: an OS delivery server that has OS data previously stored therein; an application delivery server that has application data previously stored therein; an intra-LAN server that receives the OS data from the OS delivery server and stores the OS data, activates the OS data as the OS of its own, and receives the application data from the application delivery server and stores the application data; and a network terminal device that is capable of receiving the OS data and the application data from the intra-LAN delivery server, activating the OS data as the OS of its own, and activating an application contained in the application data on the OS.