An address translation buffer (TLB) which holds pairs of virtual addresses and physical addresses by respective page sizes and performs an address translation, a storage unit which holds a pair of a virtual address removed from the TLB and page size corresponding thereto when a pair of a new virtual address and physical address read from a page table is registered to the TLB, base registers which hold a base address by each page size are held. The TLB is searched based on a translation object virtual address included in a memory access request, and when a TLB miss occurs, a main storage is searched based on a pointer address generated from information held by the storage unit and the base register, and the translation object virtual address is translated into the physical address.