1. A semiconductor storage device comprising: a first memory area provided in a semiconductor memory which performs writing of data by a first unit or less, the first unit being an access unit to the semiconductor storage device; second and third memory areas each provided in a nonvolatile semiconductor memory which performs writing of data by a second unit and performs erasing of data by a third unit, the third unit being twice or larger natural number times as large as the second unit; and a controller executing: a first processing for storing a plurality of data by the first unit in the first memory area; a second processing for storing data outputted from the first memory area by a first management unit in the second memory area, the first management unit being twice or larger natural number times as large as the first unit; and a third processing for storing data outputted from the first memory area by a second management unit in the third memory area, the second management unit being twice or larger natural number times as large as the first management unit.