The whole recording region of a recording medium (11e) such as a memory card is divided into blocks (BL1 to BLm) of a minimum size that can be expanded, and each block is divided into many a number of segments (RC1 to RCn) of a fixed length. Control data (ERBM) that indicates defective record segments in the block and control data (FLRj (j = 1, 2, ----)) of the whole file stored in the block are stored in the head region (TRA) of each of the blocks (BLi to BLm), and files are stored in the data region (DTA) other than the head region with a record as a unit. The control data (FLRj) of each file includes the record start position of file, a block number which, when the file is stored over a plurality of blocks, indicates how many blocks there are before said block, and a volume number which, when the file is stored in a plurality or recording media, indicates how many recording media there are before the one in which the block is stored.