An exemplary embodiment provides a non-transitory storage medium encoded with a computer readable program executable by the computer, for writing data in a semiconductor storage device capable of storing a plurality of bits in one memory cell. The program causes the computer to perform an allocation step of allocating a first area for storing first data in a storage area of a semiconductor storage device and a writing step of writing the first data only in an area of use, with a prescribed size from a boundary of the first area being defined as a protection area and a remaining area being defined as the area of use in response to a request for writing the first data.