1. An information processing apparatus comprising: a free page storage unit which divides a memory region in a memory into pages of a plurality of different page sizes and manages the divided pages, and stores management information about an initialization state corresponding to an unused memory region in the memory; and a page allocating unit which selects a free page of a page size according to a requested region size or a requested page size from the free page storage unit when an allocation of the unused memory region is requested, and performs an initializing process on a memory region on which the initializing process has not been performed in a memory region corresponding to the free page using management information about the selected free page.