PURPOSE:To insert a thin wire in a small through hole by furnishing a guide hole forming mechanism in such a way as possible to divide into two parts. CONSTITUTION:Moving members 4, 5 are put in contact with each other. A through hole 21 is located so as to be coaxial with a guide hole 8. When rotary shafts 10a, 10b are rotated, guide rollers 12a, 12b rotate in the directions as shown by arrows 23a, 23b. If here a wire 20 is dangled in the direction 24, the tapered portion of a guide hole 7 will guide the wire 20 till a minor dia. part provided at the bottom. The wire 20 is located by inserting it in said minor dia. part of the guide hole 7. If sunk further, the wire 20 is pinched by guide rollers 12a, 12b to be sent out forcedly downward. Thus the wire 20 is guided and located by said guide hole 8, and inserted in the through hole 21 in a bobbin 22 accurately.