PURPOSE: To prevent a molding from having any burr at the opposite end surfaces of an insert member, by constructing a mold in such a manner that one end surface of the insert member may be brought in firm contact with an end surface of a cavity.

CONSTITUTION: An insert holding member 10 that can come in firm contact with the inner circumferential walls of a cavity and one end surface of an insert member is formed with a tapered recess 10a that can be fitted onto the shaft of the insert member 10 so as to position the insert member 9. The insert member 10 is moved forward to brought in firm contact with one end surface of the insert member 9 thereby bringing the other end in firm contact with the end surface of the cavity. With this state kept, when a raw material is loaded into a space defined by the inner walls of the cavity and the outer walls of the insert member by means of injection or the like, no gap will be formed between the opposite end surfaces of the insert member and the cavity end surfaces, which prevents the formation of any burr.