Memory management device and method, and program

The invention provides a memory management device and a method. The memory management device includes a non-volatile memory that performs writing and reading of data on a per-page basis, and performs erasing on a per-block basis, and a control unit that manages a data process in the non-volatile memory by performing logical-physical translation on a per-translation unit (TU) basis, and performs a fold process. The control unit sets data of a physical TU corresponding to unnecessary logical TU information to be excluded from a copy target in the fold process based on the unnecessary logical TU information, the unnecessary logical TU information being notified of by a file system and representing a logical TU corresponding to a physical TU in which unnecessary data is physically written.