To provide a memory management technology which can be applied even in a system having no hard disk nor flash memory.

This computer system is equipped with a main storage device configured of a plurality of memory banks for managing allocation and releasing of a memory region on the main storage device. The system copies and collects data to a specific memory bank based on the situations of the allocation and releasing of the memory region in suspension, and to, when the specific memory is too small to store the data, compress and store a page whose use frequency is low, and to perform control to any memory bank other than that for the power saving by a memory power saving means.