The invention relates to a method for storing data (DATA) on a memory medium (MEM). The data (DATA) forms a file totality (FILE) and the memory medium (MEM) includes several unit-storage areas (U1-U10). At least one first bookkeeping (FDE, FAT) is maintained of the storage state of the memory medium, which consists of information of the location in the unit-storage areas of the data belonging to each file totality. In the storing process--the data is stored in the unit storage areas and--the said first bookkeeping, for example, concerning the location of the data in the unit storage areas, is updated. The data forming the said file totality is stored as file parts (file1, file2, fileN), on the data (data1, data2, . . . , dataN) of which the said storing process is performed.