In this paper, a quantitative prediction method for the gatigue limit reliability of a notched metal with different sorts of inhomogenities is proposed. The fatigue limit of the notched specimen cosists of the microcrack nonpropagation limit σω1, small crack nonpropagation limit σωd and macrocrack nonpropagation limit σω2. The reliabilities of σω1 and σωd are predicted by the stress-strength model which consists of “statistical characteristics of hardness in a small region” and “statistical characteristics of a mechanical condition in the small region containing the defect under a cyclic stress”. The σω2 is predicted by the Linear Fracture Mechanics. The present method was applied to the aluminum cast alloy JIS AC4B-T6 where eutectic Si, Fe compuound and porosity are contained. The fatigue strength at 107 tress cycles was defined as the fatigue limit. Then rotating bending fatigue tests of notched specimens with constant notch depth t =0.5 mm and various notch root radii ρ=2, 1, 0.3, 0.1 mm were carried out. The validity of the present method was examined by comparing predicted results with experimental results.