PURPOSE: To connect between the wire bobbins without suspending operation by forming a drawing-out groove in the direction tangential to a hoisting drum on the inside of one flange and forming an outer circumferential groove communicated with the drawing-out groove to the outer circumferential surface of the flange.

CONSTITUTION: The drawing-out groove 13 for an electric wire is formed to one inner surface 12a of the flange 12. The outlet 13a of the drawing-out groove 13 is communicated with the outer circumferential groove 14, and the outer circumferential groove 14 is formed in an extent of approximately two thirds as long as the length of the outer circumference of the flange 12. When the electric wire is wound on the hoisting drum 11 of the bobbin, an inner end section 1a is drawn out to the outside along the drawing-out groove 13 and wound on the outer circumferential groove 14, the electric wire 1 is wound extending over the full length of the hoisting drum 12, and wound many times so as to be stacked in succession, and an outer end section 1b is extended to the side reverse to the inner end section 1a.