Abstract: A data storage apparatus used in a form incorporated into a computer system or the like comprises a storage medium including a multiplicity of usual data regions each of which has a predetermined capacity and in or from which usual data are to be written or read and management data regions which are provided corresponding to the usual data regions or a plurality groups of usual data regions respectively and in which management data from the corresponding usual data regions are to be stored. When the writing or reading of usual data in or from a certain usual data region has resulted in a failure, management data stored in a management data region corresponding to that usual data region are rewritten.