To investigate the effect of the Si-phase on fatigue properties of Al-Si eutectic alloys in a long life fatigue range (N≤10⁷) and super long life fatigue range (N>10⁸), rotating-bending and tension-compression fatigue tests and FEM analysis were carried out. Fatigue test specimens were prepared from two materials produced by two processes: continuous casting and extrusion. The results obtained are as follows. In the case of continuous casting, all fatigue fractures were caused by shear-type cracks, resulting in shorter fatigue life. In the case of extrusion, the fatigue fracture origin in the long life fatigue range was in the Si-phase, while in the super long fatigue range it was in the matrix. The fatigue limit defined by the cycle N=10⁷ can be predicted using the √(area) parameter model, i.e. with two parameters, the maximum size of Si-phase √(area)_max and the Vickers hardness H_v of Al-marix, without the influence of the Si-phase. In the case of Al-Si alloy, a crack leading to fracture initiates even after 10⁸ cycles under very low stress. Thus, super long life fatigue behavior must be taken into account to both material and structural designs.