To provide a technology that, regardless of the capacity of a storage device, enables its areas to be flexibly partitioned and managed, and, when a file is allocated to a region also, can also use its areas effectively by means of an efficient method. When a region size of a storage device is expressed as the sum of mutually differing power-of-2 values, and areas whose size is one of the power-of-2 sizes configuring that sum are taken to be master partitions, to partition the areas into partitions each of whose size is the size made by successively dividing each master partition in half and to generate an allocation table holding allocation information expressing the allocation status of each of the files that have partitions with each of the sizes included in the master partitions. To manage a region based on the allocation information stored in the allocation table.