The object of the present invention is to protect a member from damage when a part is fit to the member. To attain the object, in the present invention, a protector 8 consisting of a hole inner side protective section 9, to protect the inside of the part fitting hole 2 of the member, and a surrounding protective section 10, to protect the surroundings of the part fitting hole, is provided, the two sections 9, 10 integrally making up the protector 8. The protector 8 is fit into the part fitting hole 2, following which a part 12 is fit thereinto.