Abstract: A positioning controller can position a head at a starting position of an unrecorded region on a disk in a shorter time than a conventional positioning controller, information being recorded on the disk by means of the sequentially inner-to-outer recording method or the sequentially outer-to-inner recording method. The positioning controller judges whether or not information is recorded at a predetermined position on the disk, and then executes the binary search method in a recording direction from the predetermined position of the disk when judged the information is recorded at the predetermined position or in a direction opposite to the recording direction from the predetermined position when it is judged that the information is not at the predetermined position. Therefore the direction in which searching by the binary search method is executed is determined by the above judgement.