Abstract: The present invention relates to an apparatus suitable for accomplishing a roll testing method. The object of the present invention is accomplished by hot rolling steel strip under the specified rolling condition using small size testing apparatus having about a tenth size of the actual rolling mill and good reciprocity like said rolling mill. The wear state (roughness), or new state, of the roll surface is estimated by a known type of surface roughness meter from the roll surface generated after hot-rolling the stell strip by the small size testing apparatus of the present invention. Said testing apparatus has the structure in which both the diameter of the rolls and the circumferential speed of the rolls are about a tenth of those of actual rolling mill and the number of the contact times (contact interval) between the rolls and the stell strip per the rolling time is the same to that of the actual rolling mill.