Rotating bending fatigue tests on smooth and notched specimens of commercially pure titanium was curried out in order to clarify fatigue strength of notched specimen. In past study, it was found that the fatigue strength of sharp notched specimens of commercially pure titanium is not clear. So, in this study, the possibility of the prediction for the fatigue strength was considered in the viewpoint of the fatigue crack initiation life N_<i>. According to the experiment results, in the smooth and notched specimens (ρ=1.0mm), there are the clear tendency of straight line relationship between the stress amplitude and the fatigue crack initiation life. And the tendency of straight line relationship of ρ=1.0mm specimen is steeper than that of smooth specimen.