PURPOSE: To prevent a part, a strip, of a guiding needle from separating or parting from the other parts thereof during treatment but to make the part easily releasable and dividable inadvertently when being unused, by providing a strip, which forms a part of a hollow tube and is made of a material different from the material of a main part of said tube, and a weld line in the middle of the strip.

CONSTITUTION: A strip 13, made of a material with different properties from those of the material of a main part 12, is longitudinally provided as an arc of the circle of a tube throughout the full length of the tube. A weld line 14 is further provided longitudinally in the substantially middle of the width of the strip 13. The weld line 14 may be formed with a dichromatic extruder 15 having two cylinders 15a and 15b. The shearing strength of the weld line 14 is controlled by adjusting the position, height, width, etc. of a baffle board 18. The shearing part of a guiding needle thus possesses necessary functions such as excessive dividability.