Management in a disk according to conventional techniques is effective in only one recording area which is the entire disk, and therefore, it has been heretofore impossible to manage files by data type.A data recording/reproducing apparatus comprises recording area setting means 50 of setting a plurality of logical recording areas in a recording medium, and file management means 60 which manages files with reference to free area management information, recording file management information and deletion file selecting criteria information, and data recording/reproducing apparatus is characterized in that when judging that a free area for writing the new data is insufficient, the file management means 60, referring to the deletion file selecting criteria information, deletes a portion or all of at least one file or does not execute an operation for writing the new data.