The present invention slides is not stray during the molding operation, as well as provided with a slide release mechanism for easily separated from the mold, which is fixed to the slide after the molding operation to be mounted in a mold to mold a portion at which the undercutting occurs in the mold, so as to tightly slide retainer fibers on-plastic mold for manufacturing with a slide release mechanism, which is provided with a for fixing, and that the mold slide is formed horizontally to a depth which is located on the top at one side of the mold, the cross-sectional an insertion hole that forms a circular or polygonal shape; At the point where the slide is located in the interior of the mold it is formed to pass through the vertical to the insertion hole, the through-hole in cross-section, which forms a round or polygonal shape; And one side of the axis of rotation is the central axis and are different from the eccentric cam is formed in the rotary shaft, and a top and bottom to be mounted in the insertion hole is in contact with the respective slide bottom and the eccentric cam top and includes a push pin mounted to the through hole and it characterized by including; slide separation apparatus.