PURPOSE: To contrive to enhance accuracy of the position of a wire guide, by a method werein a resin is charged into tapered holes provided at four corner parts of a head to integrate a wire guide and a tip part of the head to each other.

CONSTITUTION: A wire guide 12 is set in a metallic mold for injection molding which is finished with high accuracy, and a molding resin for a head nose 11 is charged into the tapered holes 13 provided at four corner parts, whereby the wire guide 12 is assembled as one body with the head nose 11 with high accuracy. Since the holes 13 are tapered, the resin charged into the holes 13 can firmly hold the wire guide 12. Since a part for setting the wire guide 12 can be formed with high accuracy when producing the metallic mold, accuracy in positioning can be maintained to be as high as the accuracy of the head nose.