To more suitably polish disk materials without severely adjusting positions of a plurality of disk materials.

The disk material polishing device is provided, which includes a retaining member 112 capable of retaining the plurality of disk materials D while leaving them from each other; a barrel member for storing the retaining member 112 for retaining the plurality of disk materials D and a polishing media; and a device for moving the barrel member. In the device, the disk materials D are polished through a first step of retaining the plurality of disk materials D by the retaining member 112 while separating them from each other, a second step of storing the retaining member 112 for retaining the plurality of disk materials D and the polishing media in the barrel member and a third step of moving the barrel member by driving the device.