According to an embodiment, a management device includes a counter storage unit, a first management information storage unit, and an update unit. The first management information storage unit stores a first management table capable of storing first management information about each of a predetermined number of first areas. The first management information indicates whether each second area included in a corresponding first area has data written therein. In response to writing of first data into the nonvolatile memory, when a state of a target second area indicated in the first management information about a target first area is an unwritten state, the update unit changes the state of the target second area to a written state; while when the state of the target second area indicated in the first management information is the written state, the update unit updates the counter value for the target first area.