A data recorder has a built-in medium recorder and a portable medium recorder. The data recorder has an optical disk drive section (14) and a HDD section (16). In addition to having a mode for recording data in either of the mediums, the data recorder has a mode for simultaneously recording data in both the mediums. A pair of directories in an HD and an optical disk, where data are to be recorded, is stored as relevance information in the HD. In the case of second simultaneous recording or subsequent simultaneous recording, a reference is made to the relevance information, thereby automating location of directories where data are to be recorded simultaneously and obviating selecting operation.