To enable further efficient use of a memory section.

This storage device 1 changes the setting so that the management area Am is changed from one processing complete state to a processing executing state by updating one minimum update area As1, of the first minimum update area As1 and a second minimum update area As2 storing one-state data, to the other state data. The storage device 1 then changes the setting so that the management area Am is changed from the processing executing state to another processing complete state by updating the other minimum update area As2, of the first minimum update area As1 and the second minimum update area As2, to the other state data. Thus, a problem wherein the management area Am is updated twice every actual data writing processing of writing actual data to an actual data storage area Ad as in a conventional method can be avoided.