PURPOSE: To attain a smooth data record/reproducing operation by holding a synchronized state of a PLL circuit by varying a data record and reproducing frequency continuously in a boundary region of an adjacent zone.

CONSTITUTION: An optical disk is driven with a MCAV system and a recording track is divided into zones Z1, Z2, Z3 and Z4 from the inner peripheral side to the outer peripheral side, boundary region R1 of the zone Z1 and the zone Z2, a boundary region R2 of the zone 2 and the zone Z3 and a boundary region R3 of the zone 3 and the zone Z4. The record/reproducing frequency of the data in the boundary region R1 varies linearly from the record/reproducing frequency of the zone Z1 to the record/reproducing frequency of the zone Z2 and the record/reproducing frequency of the data in the boundary region R2 varies linearly from the record/reproducing frequency in the zone Z2 to the record/reproducing frequency of the zone Z3 and the record/reproducing frequency of the data in the boundary region R3 varies linearly from the record/ reproducing frequency of the zone Z3 to the record/reproducing frequency of the zone Z4.