PURPOSE: To enable reduction of overhead due to page fault, by grouping any continuous plural pages and performing page in and page out processing of page group collectively.

CONSTITUTION: When a program maker prepares a linkage editor control statement collectively, for instance, from page 1 to page 3, a linkage editor 32 edits an object module 30 and forms a load module 4', and at the same time, establishes page grouping information in a set page information area 33. When the module 4' is loaded in a virtual memory 1 by a loader 34, the contents of the information area 33 are reflected on a set page mark 10 of a page table PTG. After this, page out and page in processing through page out and page in processing sections 11, 12 are processed collectively for three pages etc. Overhead due to page fault of each page of the program covering pages is reduced, and paging is performed effectively.