PURPOSE: To make uniform C/N of wobbling RF reproduced signals in prepit and pregroove area by making the track amplitude in the prepit which forms a wobbling track larger than the amplitude of the pregroove area.

CONSTITUTION: In a disk-type substrate 11 of an optical disk having a center hole 12, there are provided wobbling tracks comprising a prepit area 13 and a pregroove 14 in a sine curve along the center line of the helical virtual truck. The track amplitude in the prepit 13 is made larger by ≥10nm than that in the pregroove area 14, which prevents decrease in C/N of RF reproduced signals in the prepit 13 in the inner area. Thus, uniform C/N of wobbling RF reproduced signals is obtd. in the prepit and pregroove area. Thus, the obtd. recording medium has little read out error for wobbling RF reproduced signals in the prepit area.