Because fatigue resistance is one of the most important issues for the blanket structural materials of the fusion reactor, the fatigue damage formation processes of the advanced SiC/SiC composite (Tyranno SA 3rd/CVI-SiC composite with SiC/C multilayer interphase) for fusion reactor applications were investigated. The fatigue tests of the SiC/SiC composite were successfully performed up to 105 cycles with no significant technical issues by using a small specimen test technique developed under the IFMIF/EVEDA. Based on the evaluation of the modulus change during the fatigue tests, the tensile loading was clarified to be a dominant factor for the degradation of the SiC/SiC composite.