A disk processing apparatus having a plurality of processing units, a plurality of feed stackers, and a plurality of discharge stackers. The plurality of processing units subject label sides of disks to printing, or the like. A disk is fed from a first prior-to-being-printed stacker to the processing unit, and a processed disk is discharged to a first processed stacker. A disk is fed from a second prior-to-being-printed stacker to the other processing unit, and a processed disk is discharged to a second processed stacker. When the other processing unit is anomalous, the disk is fed from the second prior-to-being-printed stacker to the processing unit, and a processed disk is discharged to the second processed stacker, thereby performing substitute processing.