Bridging and interlocking elements, which are responsible for the stress shielding effect, are frequently observed in the wake of fatigue cracks. The crack growth curves arranged by the crack tip stress intensity factor Ktip (da/dN-Ktip curves), where the stress shielding effect is taken into consideration, almost coincide regardless of loading history, while those arranged by the apparent stress intensity factor Kapp (da/dN-Kapp curves) significantly depend on the loading history. The fatigue crack growth resistance increases with increasing grain size. The main reason for this grain size dependence is that the stress shielding effect becomes significant with increasing grain size. The crack growth curves arranged by Ktip almost coincide regardless of grain size.