1. A data control system for a computer's main memory for efficiently realizing virtualization of list structure data lying across a real memory space and a virtual memory space, comprising: a real memory space having nodes linked by pointers, with the pointers being represented by addresses in the real memory space; a virtual memory space having nodes linked by pointers, with the pointers being represented by addresses in the virtual memory space and addresses to the real memory space, and wherein the nodes in the virtual memory space are referenced to the nodes in the real memory space by indirect pointers represented by addresses of pointers in the real memory space and addresses of pointers in the virtual memory space; and means for moving the list structure data between the real memory space and the virtual memory space as list structure units.