Abstract: A vibration extraction processing unit extracts a deflection component synchronous with a rotation from a clock signal of a non-contact sensor so as to correct a clock jitter. A clock generating unit generates a clock signal of any format frequency preliminarily set up according to the clock signal from the vibration extraction processing unit. A sector correction processing unit measures an error due to the frequency deflection so as to correct the writing start position for the format pattern signal of each sector containing a servo frame signal stored in a memory according to the measured error. Writing processing units read out the corrected format pattern signal from the memory according to a synchronous signal corresponding to a single turn of a disc and a format frequency clock signal and then writes into a disc medium face.