To prevent damages to a group of wires, by arranging the constitution so that the group of wires do not contact with burrs, which arise when the worker takes out a molded protector from a mold by means of an extrusion pin.

In the protector 10 which has a body 11 U-shaped in cross section to pierce the group of wires w to be routed in an automobile, the body 11 is molded by filling resin into a cavity 3 composed of a mobile die 1 provided with a recess 1a and a fixed die 2 provided with a projection 2a to be inserted into the recess 1a. After the mobile die 1 is released, the body 11 is taken out of the fixed die 2 by pressing the extrusion pin 4 against the inner face 11a-1 of the bottom of the molded body 11 from the fixed mold 2. In sections which catch a contact section 11a-2, against which the extrusion pin 4 is pressed, ribs 13 are projected from the inner face 11a-1 of the bottom. The wire group w, passed along the inner face 11a-1 of the bottom, is pushed up by the ribs 13 so that they do not contact with burrs 20 generated at the periphery of the contact section with the extrusion pin 4.