A semiconductor storage device includes first, second, third, fourth and fifth memory areas and a controller which executes following processing. The controller executes a first processing for storing a plurality of data by the first unit in the first memory area, a second processing for storing data by a first management unit in the fourth memory area, a third processing for storing data by a second management unit in the fifth memory area, a fourth processing for moving an area of the third unit to the second memory area, a fifth processing for selecting and copying data to an empty area of the third unit in the second memory area, a sixth processing for moving an area of the third unit to the third memory area, and a seventh processing for selecting and copying data to an empty area of the third unit in the third memory area.