PURPOSE: To reproduce the data on both side surfaces without reversing a rotational direction of a disk by reading out the data on the disk recorded by a prescribed data arrangement by the rotation of in the direction opposite to the original rotational direction and converting and outputting them into the prescribed data arrangement at every block.

CONSTITUTION: The time base transformation of the input data from a read pick-up(PU) 5 is performed by a first, second buffer memories 9, 11 and the control circuit 15 of these memories and switches 7, 13. That is, the data recorded on the disk 1 in order of 1-n at every track are read out by the PU 5 in the rotational direction opposite to the original rotational direction in the order opposite to the original of n to 1 while jumping at every track. Simultaneously, these data are recorded in the memories 9, 10 alternately by controlling with the circuit 15, and are read out in the opposite order alternately, and are converted into the data order of the original 1 to n to be outputted in order of track. Thus, without reversing the rotational direction, the recording on both surfaces are reproduced normally, and a switching time of a recording surface is shortened.