The correspondence between logical addresses and physical addresses is determined so that the logical addresses in ascending order may be assigned to the physical addresses in ascending order with the physical addresses of defective blocks in a memory skipped. Then, the physical addresses of the defective blocks in ascending order are sequentially stored into the second blocks in ascending order of the physical addresses of the second blocks, respectively. To obtain a physical address from a logical address, a target block is retrieved out of a plurality of second blocks on the basis of the logical address, and the physical address of the target block is added to the logical address to obtain the physical address. Thus, it is possible to reduce the required capacity of a reserve storage region used for conversion of logical addresses into physical addresses without deteriorating the access speed.