PURPOSE: To wind wire material onto a spool in the state of the winding start end of the wire material being taken out sufficiently in length to the outside of the spool drum part to form a compact coil, and allowing the wire material to be wound in such a state that its winding start part is prevented from being crushed at the rolling time of the collar of the spool.

CONSTITUTION: A spool is provided with an under shed winding groove 60 provided at the peripheral surface of one collar 16, and a slit groove 62 provided obliquely from the outer face (the opposite side face to a drum part 22) of this collar 16 in such a way as to be communicated with the under shed winding groove 60, and a wire material hook part 64 is fitted to the outer opening part of the slit groove 62. While the winding start part of wire material 12a is being hooked to the wire material hook part 64 by the movement of a traverser, the wire material 12a is wound by one or several turns into the under shed winding groove 60 after passing the slit groove 64 and then led to the drum part 22 by the traverser so as to be wound onto the drum part 22.