Management device and management method

There is provided a management device including a management unit that manages a nonvolatile memory configured to allow data to be written, read, or erased electrically, allow writing and reading to be performed in units of a page, and allow erasing to be performed in units of a block including a plurality of pages. The management unit divides a plurality of physical blocks of the nonvolatile memory into a virtual area including virtual blocks corresponding to the physical blocks, and an alternate area including alternate blocks for replacing defective physical blocks in the virtual area, manages the nonvolatile memory in management units of three stages including management of the physical blocks, management of the virtual blocks, and management of extended blocks, and writes to the nonvolatile memory first, second, and third management information for use in the management of the physical blocks, the virtual blocks, and the extended blocks, respectively.