Abstract: A data updating system includes a current data storage unit for storing a current data. The current data includes a plurality of data rows, each of which is a set of data elements required to achieve a function. Each of the data elements is assigned with an identifier. A back-up section executes a back-up process, i.e., reads out data elements of a data row associated with an update instruction and stores it in a buffer memory. An update section overwrite new data elements designated by the update instruction on the associated data row in the storage unit in units of data elements after the back-up. When the overwrite is unsuccessful on a particular one of the new data elements, a recover section executes a recover process, i.e., reads the data elements from the buffer memory and writes them in the storage unit to recover the whole current data.