PURPOSE: To surely hold an insert and, at the same time, simplify the installation of the insert and the unloading of a molded article.

CONSTITUTION: In the fitment of an injection molder for molding a molded article by injecting resin from a fixed mold 4 under the condition that a magnetic body insert, some part of which extends beyond the molded article, is fixed to a movable mold 5, a through hole 1a is bored in the extended part 1b of the insert 1 and, in addition, a magnetic body 2 for fixing the insert 1 by attraction is imbedded at the position, which corresponds to the through hole 1a of the insert, on the mating surface 9 of the movable mold 5, so as to protrusively provide a guide pin 3, which can insert in the through hole 1a, in the magnetic body 2. At the same time, a recessed part, into which the guide pin 3 can be inserted, is formed on the matting surface 10 of the fixed mold 4.