An information record/reproduction apparatus includes logical volumes that can be used as a variable-length record/reproduction area and a physical volume that has been divided into a plurality of fixed-length areas and is not subjected to record or reproduction. Allocation to the logical volume is made by combining the divided fixed-length physical volumes by a management unit, and the size of the information storage area can be set depending upon, for example, a category of information to be recorded. If the amount of information of high priority exceeds a size of a predetermined logical volume corresponding to the information while no unused physical volume is available, then the management unit detaches part of a logical volume in which information of low priority has been recorded, allocates the detached part to the logical volume corresponding to the information, and thus records the exceeding amount of information.