The purpose of this work is to investigate the effect of relief groove radius and the taper in gradual diameter change of shaft on stress concentration factors. Finite element analysis was used to conduct theoretical research in order to reduce the maximum value of stress in stepped shafts. In comparison based on a straight shaft without relief groove, the results show the decrease of taper angle has a significant effect in decrease the values of stress concentration factors. On the other hand, the increase of location of relief grooves from shaft shoulder tends to increase the stress concentration factors values, especially at high taper angle.