The authors have made two kinds of fatigue tests on shoulder fillet specimens (one is 135 mm in diameter at the testing part and 15 mm, 25 mm and 40 mm in fillet radius, the other is 14 mm in diameter, having proportional sizes to larger one), for the purpose of obtaining fatigue notch factor on shoulder fillet by comparing their fatigue limit with those of 125 φmm and 10 φmm smooth surface specimens described in Part 1. On the other hand the stress concentrating factor has been determined on fillet of larger specimen, by correcting the effect of the ratio of gauge length to fillet radius. This correcting factors are 1.06, 1.018 and 1.006, where the above ratios are 0.60, 0.36 and 0.225 respectively. It has been disclosed from these tests that : (1) Stress concentrating factor given by Petereon is equal to the measured value without correction. ( 2 ) Fatigue notch factors of larger sepcimen are nealy equal to those of smaller ones ; and coincide with the corrected concentrating factor of quivalent stress by shear strain energy theory.