An optical disk is equipped with a hub which is very easy to attach and detach. The hub has a bottom and a cylindrical wall which projects upwards from the bottom, and which is inserted in the center hole of the optical disk. The cylindrical wall of the hub is slotted so that the upper end of the cylindrical wall can be bent radially inwards to a smaller diameter allowing removal of the hub from the optical disk. The hub further has stoppers, formed at or near the bottom, for abutting the lower surface of the optical disk, and claws formed at or near the upper end of the cylindrical wall, for abutting on the upper surface of the optical disk.