A holding device is provided with adapters capable of dealing with a case where the hollow shaft portions of a roll-like fixing medium differ in inner diameter. Thus, it is unnecessary to have a complete set of roll paper supporting members to be used every time the hollow shaft portions of the roll-like fixing medium differ in inner diameter. As the size of such an adapter can be made at least smaller than the size of the roll paper supporting members, the adapter is easily stocked under control.