Burr occurs at the bottom of the material as the material breaks during shearing, and sliver occurs in shear droop that occurs when a punch penetrates the surface of the material. Sliver refers to the shape of a long and thin thread, and it is an important defect that can cause a short when assembled into electronic parts other than a defect in the appearance of a product, an assembly defect in the post-process, and an injury to the operator. Sliver does not occur when the molding is completed only by the main shearing without pre-shearing, but sliver occurs when the main shearing is performed after the pre-shearing. The purpose of this study is to study the sliver generation mechanism that occurs during main shearing after pre-shearing. Using the material phosphor bronze C5210-EH(HP), the sliver was observed with the dimensions and stripping force of the pre-shearing as variables, and the effect of the pre-shearing on the sliver was studied. The product used in the experiment is a terminal, a press product that is assembled on a 0.4mm pitch FPC connector. Three experimental variables were selected: the X-axis allowance, the Y-axis length, and the stripping force in the dimensions of the pre-shearing. As a result of 12 experimental conditions, the X-axis allowance had a greater effect on sliver generation than the Y-axis length and stripping force. The cause of sliver during pre-shearing is that the shear droop part is elongated due to bending when the punch is lowered due to the hole in the bottom due to pre-shearing.