A recording medium comprising a recording area, wherein
the synchronization code sequence (SY) which is to be recorded in the frame area located at the start of a fourth area (3103) is different by a code distance equal to or greater than 2 in NRZI representation from any synchronization code sequence which is to be recorded in any of frame areas of the fourth area other than the frame area located at the start of the fourth area.
A binarizing unit holding a threshold value for use in the binarization during a time period in which the reading signal includes a predetermined signal.
