PURPOSE: To enable exact judgement by discriminating the adequateness only when the extent of the movement in the stage of loading a winding stem with a weight which needs not be drawn out is smaller than a specified value and the extent of the movement in the stage of loading the same with a weight which must be drawn out is larger than the specified value.

CONSTITUTION: An operator pushes a start button 26 to start the operation of a CPU23. The fore which must not be drawn out, i.e., 150g, is then drawn out and is loaded to the winding stem by a solenoid valve 27 and the extent of the movement of the winding stem is detected via an analog-to-digital converter 22 by an element 21 for detecting the extent of the movement by utilizing an electromagnetic induction effect. The detected extent of the movement is compared with the specified extent of the movement set in the CPU23 and a reject lamp 25 is lighted up if said extent is larger. The force which must be drawn out, i.e., 500g, is loaded to the winding stem by a solenoid valve 28 if said extent is smaller. The extent of the movement is then detected by the element 21 and is compared with the specified extent of the movement. The lamp 25 is lighted up if the result thereof is smaller and an accept lamp 24 is lighted up if said result is larger. The operation is thus completed.