PURPOSE: To easily access a file on other host through a network by a user by mapping the file on the host through the network to user space.

CONSTITUTION: A page table maps the page of virtual space to a physical page. A network page table maps the page of the host through a network 6. A referring counter table includes the file page on the secondary storage of a self-machine and the number of the program to refer to the file page. The arbitrary file on the secondary storage of the arbitrary machine linked with the network 6 is mapped to the virtual storing space of a user and the access to the virtual storing space of the user is automatically converted to the access to a secondary memory 5.