According to one embodiment, a nonvolatile semiconductor memory drive includes a nonvolatile semiconductor memory, and a controller which controls a process of writing and reading data with respect to the nonvolatile semiconductor memory. The controller includes a compaction control module which acquires free groups set in an unused state by rearranging valid data scattered in n groups in groups of a number not larger than n−1 when the number of free groups remaining in a plurality of groups formed as a storage area management unit of the nonvolatile semiconductor memory becomes not larger than a predetermined number, and a compression control module which acquires free groups by compressing stored data in m groups in which access to stored valid data has not been made for a period longer than a predetermined period and rearranging the compressed data in groups of a number not larger than m−1.