To shorten stopping time of a line, and to improve an equipment operation rate by providing a gripping means for gripping a platelike material and a moving means for moving along a mill path line by mounting the gripping means.

A mill roller 1 is rotated to be inserted between upper/lower blades of shears in an opening state, and the tip of a steel strip 2 is inserted into a nipper link 42 in an opening state. The steel strip tip is nipped by closing the nipper link 42. A sample material is sheared from the steel strip by actuating the shears 4. A support roller is housed inside a tip arm. Next, a telescopic arm 22 is contracted. The telescopic arm is retreated in a state of sandwiching the sample material so that the sample material is brought under a printing head 70. The printing head 70 is lowered to print an identification signal on the sample material. The nipper link 42 is opened so that the sample material is recovered in a sample material recovering bag 11.