Abstract: A mold for molding plastic products includes a fixing plate and a moving plate which is movable toward and away from the fixing plate. The fixing plate and the moving plate include respective cavity-forming portions which form a cavity into which a melted plastic is injected so as to form a molded product. A plurality of molding pins is provided having prominence-depression portions positionable in the cavity for forming undercut portions in the molded product, the molding pins being slidable through the moving plate by an eject plate. The molding pins pass obliquely through the moving plate so that as they slide therethrough, their prominence-depression portions are separated from the undercut portions of the product. Two of the molding pins form on the product a partition wall having undercut portions at opposite sides thereof. Those two molding pins cross over one another so that the prominence-depression portions thereof face each other, with no part of the cavity-forming portions situated therebetween.