In the field welding division for I-section girders, the web plate generally possesses semi-circular notches called as cope holes in order to avoid intersection of weld lines. The cope holes induce out-of-plate bending stresses caused by shear force in addition to membrane stresses by bending moment in I-section girders. Therefore, a local stress concentration occurs in the vicinity of a cope hole. This study aims at investigating fatigue strength of cope hole details in the mixed joint that were made both welded flanges and high strength bolted web. For this purpose, fatigue tests were carried out of on the large-scale girder specimens with cope holes in the mixed joints.