Administration device, administration method, and program

An administration device includes an administration section. The administration section administers writing, reading, and erasing of data in a nonvolatile memory, in which the data can be electrically written, read, and erased and the writing and the reading are performed on a page-by-page basis and the erasing is performed on a block-by-block basis, by translating a logical address into a physical address on a per translation unit basis; and performs fold processing of increasing unwritten physical translation units by the number of written invalid physical translation units, which are contained in a block of a copy source, by copying data of written valid physical translation units among the contents of the block into a block, in which the unwritten physical translation units reside, and by erasing the block of the copy source.