A method of designating a disk recording capacity and an optical disk recording apparatus using the method, where a maximum recording capacity is designated by measuring an external disturbance for disk regions. The method of designating a disk recording capacity includes: partitioning a disk into a plurality of disk regions, and measuring external disturbance at the disk regions; setting a disk speed based on the measured external disturbance, and designating disk regions excluding the disk regions where the external disturbance is measured as recordable disk regions; and calculating a maximum disk recording capacity based on the designated recordable disk regions.