The blanking of thin sheet metals using progressive dies is an important process on production of precision electronic machine parts. As a model of IC leadframe, an I-shaped and an Lshaped models were blanked and influences of blanking conditions on dimensional accuracy of blanked lead were examined. Furthermore, a mechanical model is proposed to explain the affect of the blanking conditions on product accuracy. In these days, more fine leads are required as electronic machines become more precise and accurate. It must be treated that leads are firmly held for blanking leadframes accurately. In this paper, an effective method of stripper holding leads strongly are discussed and a new method using newly designed stripper is proposed. Consequently the effect of it on lead accuracy is proved.